The identification of temporary horizontal leaders in projects: The case of China

Balanced leadership in projects describes the dynamic transition of leadership authority between the project manager and one or more team members. Within this concept, the present study investigates the context, criteria, and processes for identifying project team members as candidates for the role of horizontal leader. Five case studies, followed by validation interviews were conducted in China. Results show that structure and agency by the project manager set the context, wherein professionality, personality and attitudinal characteristics of team members are evaluated for identification. This is executed in two parallel processes, where the project manager evaluates, develops and assesses candidates, and the team members evaluate their situation, compete with others, develop their skills, and look for guidance from the project manager. Managerial and theoretical implications are discussed.     

Modellbasierte Berechnung der Abfluss- und Stofftransportprozesse in hierarchisch organisierten Karstnetzwerken

Karst systems fed by an allogenic inflow often show a complex network of interacting conduits that effects groundwater flow and pollutant transport. The combined evaluation of multi-tracer experiments performed at different flow conditions provide information about the hydrodynamic functioning of the karst network. Building on this, a conceptual model to quantify groundwater flow and mass transport has been developed and is presented in this study using the example of the Tanneben Massif, Austria. Within the model, groundwater flow is subdivided into several flow-paths with discrete flow velocity and capacity. As a consequence, model results reveal a dampen but also extended karst response to storm events. Upon exceeding the flow capacity, backwater accumulates at the inflow causing a prolongation of high discharge into the system. Additionally, adjacent karst systems are affected by the activation of interconnecting flow paths at high flow conditions.     

Using silicone passive samplers to detect polycyclic aromatic hydrocarbons from wildfires in streams and potential acute effects for invertebrate communities

Silicone rubber passive samplers spiked with 4 deuterated performance reference compounds were deployed for 29-33 days to estimate the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in 9 streams in Victoria, Australia, following a wildfire. Silicone rubber strips of 2 thicknesses were used to obtain information on the status of uptake of the chemicals of interest at retrieval. In addition, we monitored the stream macroinvertebrate community for potential effects of PAHs or other fire organics. All selected PAHs were detected in the passive samplers and the sampling rates ranged from 0.5 to 50 L/day significantly varying between sites but not compounds, presumably due to differences in current velocity. The estimated water concentrations were 0.1-10 ng/L for total PAHs with phenanthrene, pyrene and fluoranthene accounting for 91% of the total concentration. All PAHs were a factor of 1000 or more below the reported 48-h median lethal concentrations (48-h LC50) for Daphnia magna. Two sites located closest to the fires exhibited elevated concentrations compared to the other sites and the passive samplers in these sites remained in the integrative uptake regime for all compounds, suggesting precipitation-associated PAH input. No acute toxic effects of PAHs or other fire organics on the invertebrate community were detected using a biotic index for organic toxicants (SPEAR), whereas a non-specific biotic index (SIGNAL) decreased in two sites indicating impacts from changes in other environmental parameters. We conclude (1) that silicone-based passive samplers with two different area-to-volume ratios represent a promising tool for determining organic toxicants and (2) that PAHs from wildfires are unlikely to be a common main cause for fire-related ecological effects in streams adjacent to burnt regions.     

A comparison of human pharmaceutical concentrations in raw municipal wastewater and yellowwater

Currently, many articles report on pharmaceutical residues detected in various compartments of the environment. A major pathway into the aquatic environment is municipal wastewater. This article discusses the relevance of yellowwater (urine) as pharmaceutical source within this wastewater stream. Literature data about concentrations of 28 pharmaceutical residues detected in raw wastewater are compared to their theoretically calculated concentrations in urine. The study shows that these pharmaceuticals and their metabolites are excreted predominantly via urine although some substances show reasonable excretion via faeces. It is demonstrated that the influence of pharmacokinetic activities is one important issue affecting the presence of pharmaceuticals in the aquatic environment. Nevertheless, only a weak correlation between concentrations of pharmaceuticals calculated in yellowwater and analysed in raw wastewater was observed. This is due to environmental effects taking place between the excretion of urine and the entrance of sewerage into the wastewater treatment plant. The data show that urine separation and separate handling/treatment of this wastewater stream represents a promising approach to protect the aquatic environment safely from human pharmaceuticals.     

Erneuerung von Großbrücken im Zuge hoch belasteter Autobahnen – Randbedingungen und Lösungsansätze am Beispiel der Urselbach‐Talbrücke

Renewal of highly frequented large‐scale motorway bridges. The bridge over the Urselbach – edge conditions and solutions. The newly built bridge across the Urselbach, which has a total length of 332 m, is part of the Federal Highway A5 near Frankfurt. The construction is composed of two bridges, one for each carriageway. Each superstructure consists of two steel box girders. Over these steel box girders, and resting on their top flange, is a cast‐in‐place concrete slab that becomes a part of the roadway. For a future renewal of the concrete slab it is requested that eight traffic lanes still have to remain during reconstruction. As one superstructure is passed by maximum six traffic lanes, the other must still be partly passable during its renewal. That's why the concrete slab can be demolished partly and afterwards concreted if it's necessary. Therefore the composite construction offered many advantages. The form of composite construction of the bridge across the Urselbach results from the combined action of structural steel and a concrete deck slab, which has the function of a replaceable structural member under traffic use. This conception was achieved by a structural analysis taking the substantial influences into account and the arrangement of some additional structural parts. The found solution should give some ideas on the way to a technical guide‐line for dimensional and structural design of concrete bridges with replaceable deck slabs.     

Electrical Conductivity of Mullite Ceramics

The electrical conductivity of a lab‐produced homogeneous mullite ceramic sintered at 1625°C for 10 h with low porosity was measured by impedance spectroscopy in the 0.01 Hz to 1MHz frequency range at temperatures between 300°C and 1400°C in air. The electrical conductivity of the mullite ceramic is low at 300°C (≈0.5 × 10^?9 Scm^?1), typical for a ceramic insulator. Up to ≈ 800°C, the conductivity only slightly increases (≈0.5 × 10^?6 Scm^?1 at 800°C) corresponding to a relatively low activation energy (0.68eV) of the process. Above ≈ 800°C, the temperature‐dependent increase in the electrical conductivity is higher (≈10^?5 Scm^?1 at 1400°C), which goes along with a higher activation energy (1.14 eV). The electrical conductivity of the mullite ceramic and its temperature‐dependence are compared with prior studies. The conductivity of polycrystalline mullite is found to lie in‐between those of the strong insulator α‐alumina and the excellent ion conductor Y‐doped zirconia. The electrical conductivity of the mullite ceramic in the low‐temperature field (< ≈800°C) is approximately one order of magnitude higher than that of the mullite single crystals. This difference is essentially attributed to electronic grain‐boundary conductivity in the polycrystalline ceramic material. The electronic grain‐boundary conductivity may be triggered by defects at grain boundaries. At high temperatures, above ≈ 800°C, and up to 1400°C gradually increasing ionic oxygen conductivity dominates.     

The Mitochondrial Amidoxime Reducing Component (mARC): Involvement in Metabolic Reduction of N‐Oxides,Oximes and N‐Hydroxyamidinohydrazones

The mitochondrial amidoxime reducing component (mARC) is a molybdenum‐containing enzyme and capable of reducing N‐hydroxylated structures such as amidoxime prodrugs. In this study, we tested the involvement of mARC in the reduction of N‐oxides (amitriptyline‐N‐oxide, nicotinamide‐N‐oxide), oximes ((E)‐/(Z)‐2,4,6‐trimethylacetophenonoxime) and a N‐hydroxyamidinohydrazone (guanoxabenz). All groups are reduced by mARC proteins, and the enzymes are therefore involved in the interconversion of N‐oxygenated metabolites originating from cytochrome P450s and flavin‐containing monooxygenases. In addition, these structures open up further options for serving as prodrugs. Thus, with respect to these reactions, testing of candidates with N‐oxygenated structures should not solely be carried out in microsomal enzyme sources but as well in mitochondria. However, differences in the reduction of oximes and N‐oxides between the two isoforms, namely mARC1 and mARC2, were detectable; N‐oxides are exclusively reduced by mARC1. We therefore assume differences between the so far unknown 3D structures of the two proteins.     

Apertureless near-field optical microscopy: differences between heterodyne interferometric and non-interferometric images

We analyze simulations of the image generation process in apertureless Scanning Near-Field Optical Microscopy to study the differences between heterodyne interferometric and non-interferometric detection schemes implemented in experiments. Beyond the well-known possibilities of interferometry to enhance signals and extract optical phase information, we find that heterodyne interferometric detection may in fact lead to more robust and easier to interpret experimental results. Further, our results illustrate how simulations that do not include the use of interferometric detection in a given experiment can lead to significant disagreements with the measurements.     

Periodic operation applied to the kinetic study of CO2 methanation

Periodic operation was applied to the CO₂ methanation reaction at 383 K on 2% Ru/TiO₂. A continuous feed recycle reactor combined with a diffuse reflectance infrared cell and a mass spectrometer allowed to follow simultaneously the gas phase CO₂ and CH₄ as well as the adsorbed species (CO)_a and (formate)_a. Experiments consisting of periodic variations of CO₂ in the hydrogen feed showed response curves with maxima/minima shifted in time in the sequence CO₂, (formate)_a → (CO)_a → CH₄. Similar delays measured for the (CO)_a formation and hydrogenation indicate that both of these processes are limiting the overall reaction rate. A kinetic model was proposed and verified under periodic conditions. The main experimental trends, which are pronounced time lags between CO₂, (CO)_a and CH₄, could be described satisfactorily.     

Vapor induced crystallization of syndiotactic random copolymers of styrene with p-n-butylstyrene

Summary. The vapor induced modification of bulk samples of syndiotactic random copolymers of styrene and p-n-butylstyrene is studied by wide-angle X-ray scattering and light microscopy. Two samples with p-n-butylstyrene contents of 4 and 11 mol% are compared. It is shown that treatment with CHCl₃ leads to the formation of a clathrate modification similar to that of neat syndiotactic polystyrene. The change of the surface topography of the copolymers as a result of CHCl₃ vapor exposition is studied by tapping-mode/height-mode atomic force microscopy. Received: 4 November 1997/Accepted: 27 November 1997