Showing papers by "Braunschweig University of Technology published in 2006"
TL;DR: Health information systems (HIS) have become one of the most challenging and promising fields of research, education and practice for medical informatics, with significant benefits to medicine and health care in general.
709 citations
TL;DR: In this paper, the authors examined the relationship between routinization and four work character istics (job control, job complexity, time pressure, and supervisor support) and a range of creative and proactive behaviors on the other hand.
Abstract: Summary Researchers have claimed that routinization hinders creativity. However, empirical evidence for this assumption is sparse. In this study, we argue that routinization may be beneficial for creativity and related behavior due to available resources that can be used to develop new ideas while working. We examine the relationship between routinization and four work character istics (job control, job complexity, time pressure, and supervisor support) on the one hand and a range of creative and proactive behaviors on the other hand in a randomly selected sample of 278 employees of a German high tech company. Regression analyses reveal that in addition to work characteristics, routinization is generally positively related to creative and proactive behaviors. Ways to enhance routinization and thereby creative and proactive behaviors are discussed.
500 citations
TL;DR: The genome sequence provides the basis for the future design of strategies to mitigate the ecological damage caused by oil spills and provides A. borkumensis SK2 with a competitive edge in oil-polluted environments.
Abstract: Alcanivorax borkumensis is a cosmopolitan marine bacterium that uses oil hydrocarbons as its exclusive source of carbon and energy. Although barely detectable in unpolluted environments, A. borkumensis becomes the dominant microbe in oil-polluted waters. A. borkumensis SK2 has a streamlined genome with a paucity of mobile genetic elements and energy generation-related genes, but with a plethora of genes accounting for its wide hydrocarbon substrate range and efficient oil-degradation capabilities. The genome further specifies systems for scavenging of nutrients, particularly organic and inorganic nitrogen and oligo-elements, biofilm formation at the oil-water interface, biosurfactant production and niche-specific stress responses. The unique combination of these features provides A. borkumensis SK2 with a competitive edge in oil-polluted environments. This genome sequence provides the basis for the future design of strategies to mitigate the ecological damage caused by oil spills.
415 citations
TL;DR: In this paper, the authors present an overview of the current state of the art in modeling and simulation of grinding processes: physical process models (analytical and numerical models) and empirical process models(regression analysis, artificial neural net models) as well as rule based models (rule based models) are taken into account.
406 citations
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350 citations
TL;DR: The transition element molybdenum (Mo) is of essential importance for (nearly) all biological systems as it is required by enzymes catalyzing diverse key reactions in the global carbon, sulfur and nitrogen metabolism.
321 citations
TL;DR: In this paper, the authors demonstrate that this vision is on the verge of becoming reality by using transparent thin-film transistors (TTFTs) as pixel drivers for fully transparent displays.
Abstract: Fully transparent computer displays have, until now, been the vision of science-fiction movies. Nevertheless, there are numerous applications for these devices ranging, for example, from head-mounted displays to their integration in automotive windshields. In this paper we demonstrate that this vision is on the verge of becoming reality. The realization of entirely transparent displays requires both transparent light-emitting devices, in our case organic light-emitting diodes (OLEDs) with transparent contacts, and a driving scheme based on transparent thin-film transistors (TTFTs). Since the early reports on electroluminescence from multilayer, thin-film devices composed of vacuum-sublimed small organic molecules [1] and spin-coated conjugated polymers, [2] substantial research has been devoted to the improvement of device efficiencies, color purity, and lifetime. Incitement of this development is the potential use of OLEDs in future commercial flat-panel displays. OLEDs usually consist of a layer sequence of organic functional materials (charge transporters/blockers/emitters) with an overall thickness of the order of 100 nm. Most of these materials absorb light in the deep-blue or ultraviolet spectral region and are nearly transparent in the visible part of the spectrum. Organic layers applied to emit visible light are often based on so-called guest–host systems, in which a wide-bandgap host material (absorbing in the UVonly) is doped with a few weight percent of a light-emitting dye. [3] As a result, the emitting layer appears transparent. Transparent conductive oxides, most prominently indium tin oxide (ITO) and aluminum-doped ZnO (AZO), may be used as electrical contacts to OLEDs. Therefore, OLEDs seem to be promising devices for the realization of entirely transparent visible-light emitters. [4–6] OLED displays driven in passive-matrix mode are based on conventional bottom-emitting OLEDs and are considered as an approach to fabricate small-sized, low-information-content displays with moderate pixel counts. To accomplish largerarea, high-resolution OLED displays an active-matrix-addressing scheme has been suggested. [7] Conventional a-Si:H or poly-Si TFT backplanes are not suitable as drivers for transparent displays because they are opaque in the visible part of the spectrum. Putting pixels and transistors next to each other would compromise the displays’ fill factor. Organic field-effect transistors (OFETs) as pixel drivers for OLEDs have been discussed by Sirringhaus et al. [8] Transparent OFETs have also been reported. [9] However, their performance is still poor; transparent active pixels using OFETs have not yet been demonstrated. Therefore, in this paper we focus on the production of TTFTs based on the wide-bandgap oxide semiconductor zinc tin oxide (ZnO)x(SnO2)1–x ,a s a viable alternative to previously fabricated devices. Recently, research on TTFTs with channels made from ox
316 citations
TL;DR: The molybdenum cofactor (Moco) forms the active site of all eukaryotic moly bdenum (Mo) enzymes and is essential for purine degradation and stress response.
Abstract: The molybdenum cofactor (Moco) forms the active site of all eukaryotic molybdenum (Mo) enzymes. Moco consists of molybdenum covalently bound to two sulfur atoms of a unique tricyclic pterin moiety referred to as molybdopterin. Moco is synthesized from GTP by an ancient and conserved biosynthetic pathway that can be divided into four steps involving the biosynthetic intermediates cyclic pyranopterin monophosphate, molybdopterin, and adenylated molybdopterin. In a fifth step, sulfuration or bond formation between Mo and a protein cysteine result in two different catalytic Mo centers. There are four Mo enzymes in plants: (1) nitrate reductase catalyzes the first and rate-limiting step in nitrate assimilation and is structurally similar to the recently identified, (2) peroxisomal sulfite oxidase that detoxifies excessive sulfite. (3) Aldehyde oxidase catalyzes the last step of abscisic acid biosynthesis, and (4) xanthine dehydrogenase is essential for purine degradation and stress response.
296 citations
TL;DR: This survey focuses specifically on polygonal shape functions that satisfy the properties of barycentric coordinates: form a partition of unity, and are non-negative; interpolate nodal data (Kronecker-delta property), and are smooth within the domain.
Abstract: This paper is an overview of recent developments in the construction of finite element interpolants, which areC
0-conforming on polygonal domains. In 1975, Wachspress proposed a general method for constructing finite element shape functions on convex polygons. Only recently has renewed interest in such interpolants surfaced in various disciplines including: geometric modeling, computer graphics, and finite element computations. This survey focuses specifically on polygonal shape functions that satisfy the properties of barycentric coordinates: (a) form a partition of unity, and are non-negative; (b) interpolate nodal data (Kronecker-delta property), (c) are linearly complete or satisfy linear precision, and (d) are smooth within the domain. We compare and contrast the construction and properties of various polygonal interpolants—Wachspress basis functions, mean value coordinates, metric coordinate method, natural neighbor-based coordinates, and maximum entropy shape functions. Numerical integration of the Galerkin weak form on polygonal domains is discussed, and the performance of these polygonal interpolants on the patch test is studied.
286 citations
TL;DR: In this article, the authors examined job stressors, job involvement, and recovery-related selfefficacy as predictors of psychological detachment in a sample of 148 school teachers, assessed by self-reports and by ratings provided by family members.
Abstract: Previous research has suggested that psychological detachment from work during off-job time is important in order to recover from stress encountered at the job. Psychological detachment refers to an individual's experience of being mentally away from work, to make a pause in thinking about work-related issues, thus to “switch off”. This study examines job stressors, job involvement, and recovery-related self-efficacy as predictors of psychological detachment in a sample of 148 school teachers. Psychological detachment was assessed by self-reports and by ratings provided by family members. Multiple regression analysis showed that workload, job involvement, and recovery-related self-efficacy were significant predictors of both self-rated and family-rated psychological detachment. The study findings suggest that with respect to practical implications it is crucial to manage workload and to increase recovery-related self-efficacy.
273 citations
Austrian Academy of Sciences1, Chinese Academy of Sciences2, Braunschweig University of Technology3, Imperial College London4, University of California, Los Angeles5, Swedish Institute of Space Physics6, University of Sheffield7, Slovak Academy of Sciences8, European Space Research and Technology Centre9
TL;DR: In this article, the authors compare the magnetic field experiment of the upcoming Venus Express mission with the long lasting Pioneer Venus Orbiter (PVO) observations with respect to the solar wind interaction with Venus.
TL;DR: Investigation of individuals' personal and perceived cultural norms and their relation to social anxiety and fear of blushing provides initial evidence that social anxiety may be related to different cultural norms across countries.
TL;DR: This paper considers algorithms for computing the response of a coupled problem with a partitioned approach, and why this approach may experience difficulties, and how they may be circumvented with Newton-like methods still staying in the partitioned framework.
TL;DR: In this article, the effects of polypropylene (PP) fibres on the residual mechanical strength of high performance concrete (HPC) specimens at elevated temperatures were also investigated.
TL;DR: In this paper, the authors present laboratory experiments on the formation of macroscopic dust aggregates and find packing densities between 0.07 and 0.15 for uncompressed samples, dependent on the shape and size distribution of the constituent dust grains.
Abstract: We present laboratory experiments on the formation of macroscopic dust aggregates. The centimeter-sized highly porous bodies are produced by random ballistic deposition from individual micrometer-sized dust particles. We find packing densities between 0.07 and 0.15 for uncompressed samples, dependent on the shape and size distribution of the constituent dust grains. Impacts into these bodies are simulated by uniaxial compression experiments. We find that the maximum compression, equivalent to the highest protoplanetary impact velocities of ~50 m s-1, increases the packing density to 0.20-0.33. Tensile strength measurements with our laboratory samples yield values in the range 200-1100 Pa for slightly compressed samples. We review packing densities and tensile strengths found for primitive solar system bodies, e.g., for comets, primitive meteorites, and meteoroids. We find a consistency between packing densities and tensile strengths of our laboratory samples with those from cometary origin.
TL;DR: Projects that could improve understanding of voltinism in the context of seasonal regulation and the main types of odonate life cycle so far recognised are suggested.
Abstract: We classified 542 records of voltinism for 275 species and subspecies of Odonata according to three variables: geographical latitude, systematic position and habitat type. We sorted records according to voltinism—categories being three or more generations per year, two generations per year, one generation per year, one generation in two years and one generation in three or more years. We sought to correlate the voltinism of each record with latitude of the study site, thus demonstrating an overall negative correlation between voltinism and latitude. After allowing for phylogenetic similarity a negative correlation remains, although it decreases in strength after removal of taxonomic correlates, mainly between family and genus levels. A negative correlation exists at the species level within most families, with the exception of Lestidae. In genera for which we lacked data for latitudes 0-31°N/S no significant correlation between latitude and voltinism exists. In temporary waters most species compl...
TL;DR: In this article, the authors extended the Lattice Boltzmann (LB) method to simulate multi-phase flows on non-uniform tree-type grids, and showed that the maximum number of possible grid levels for problems with dominant capillary forces is very restricted if the physical interface is allowed to pass over grid interfaces.
TL;DR: Kinetic, electrochemical, and EPR analyses provide unequivocal evidence that the hypothetical proteins from Bacteroides thetaiotaomicron and from E. coli, which are closely related to the deduced protein encoded by the RL5 gene, are also multicopper proteins with polyphenol oxidase activity.
TL;DR: The static and high frequency dielectric tensors, Bom effective charges, vibrational spectrum at the Γ point, TO-LO splitting and IR intensities of calcite CaCO 3 have been calculated with the periodic ab initio CRYSTAL program, with five different basis sets of increasing size and four different Hamiltonians as mentioned in this paper.
Abstract: The static and high frequency dielectric tensors, Bom effective charges, vibrational spectrum at the Γ point, TO-LO splitting and IR intensities of calcite CaCO 3 have been calculated with the periodic ab initio CRYSTAL program, with five different basis sets of increasing size and four different Hamiltonians (HF, LDA, PBE, B3LYP). B3LYP is shown to perform better than the other options, in particular of LDA and PBE that are often used for the calculation of the vibrational spectrum of crystalline solids. When comparing B3LYP and experimental frequencies, the mean absolute difference is as small as 8.5 cm -1 ; this number reduces to 4.8 cm -1 if the two lowest experimental frequencies, that we suspect to be affected by a relatively large error, are excluded from statistics. Static and high frequency dielectric tensors, as well as IR intensities computed with the same hybrid scheme (B3LYP) compare quite favourably with experiment. The full set of modes is characterized by various tools including isotopic substitution, "freezing" one of the two subunits (Ca 2+ or CO 3 2- ) and graphical representations. A general tool has been implemented, that permits the automatic generation of the animation of the full set of modes starting from the CRYSTAL output (available at www.crystal.unito.it/vibs/ calcite).
TL;DR: In this paper, the authors compare the accuracy and computational efficiency of two research simulation codes based on the LB and the finite element method (FEM) for two-dimensional incompressible laminar flow problems with complex geometries.
TL;DR: In this paper, the influence of an active seed metabolism on the observed alterations of the sugar concentrations is discussed, and a comparison with the untreated controls revealed that the low levels of both hexoses are the consequence of a decrease in the case of wet processing, whereas they remained unchanged or even increased in dry processing.
Abstract: Quantitative analyses of low molecular sugars in green coffees (Coffea arabica L. var. Acaia) that were processed in parallel either by the traditional wet or the traditional dry method, revealed a close correlation between the kind of post-harvest treatment and the contents of fructose and glucose. While in washed coffee beans (wet processing) only low amounts of these both hexoses were present, those in unwashed coffees (dry processing) were significantly higher. Model-processing experiments in the laboratory confirmed these findings. Moreover, a comparison with the untreated controls revealed that the low levels of both sugars are the consequence of a decrease in the case of wet processing, whereas they remained unchanged or even increased in the case of dry processing. Further minor sugars are also affected by post-harvest treatment. The amounts of galactose, arabinose and mannose show a similar arrangement as those for glucose and fructose, although their overall concentration is about 100-fold lower. Sucrose, the major low molecular sugar in green coffee beans, is not significantly affected by coffee processing. The influence of an active seed metabolism on the observed alterations of the sugar concentrations is discussed.
12 Sep 2006
TL;DR: A low-cost system for 3d data acquisition and fast pairwise surface registration and the only hardware requirements are a simple commercial hand-held laser and a standard grayscale camera is proposed.
Abstract: In the last twenty years many approaches for contact-free measurement techniques for object surfaces and approaches for 3d object reconstruction have been proposed; but often they still require complex and expensive equipment. Not least due to the rapidly increasing number of efficient 3d hard- and software system components, alternative low-cost solutions are in great demand. We propose such a low-cost system for 3d data acquisition and fast pairwise surface registration. The only hardware requirements are a simple commercial hand-held laser and a standard grayscale camera.
TL;DR: In this article, the effects of different RCA replacement percentages (i.e., 0, 30, 50% and 100%) on the seismic performance of the reinforced recycled aggregate concrete frames are emphasized and analyzed in detail.
TL;DR: This article shows how a relevance-based, altruistic communication scheme helps realize scalability by optimizing the application benefit and the bandwidth usage.
Abstract: Intervehicle communication (IVC) and its diverse application possibilities are experiencing growing interest both in research and industry. The dissemination of active safety messages generated by context-sensitive applications in vehicular ad hoc networks (VANETs) promises to improve passenger safety and comfort. One of the main challenges inherent to the deployment of VANETs is operability, both in very sparse and in highly overloaded networks. This scalability problem is not comprehensively addressed by existing approaches, as they only focus on parts of the problem. This article shows how a relevance-based, altruistic communication scheme helps realize scalability by optimizing the application benefit and the bandwidth usage. In-vehicle and intervehicle message selection are based on a relevance function that makes use of the current context and the content of the messages. A novel, proprietary cross-layer architecture and an IEEE 802.11e-based architecture can be used to implement the scheme
TL;DR: In this article, a large-format long-distance micro-particle image velocimetry system (μ-PIV) was developed to measure the wall-shear-stress and the near-wall flow properties in a laminar, transitional and turbulent boundary layer flow along a flat plate, non-intrusively with high accuracy and spatial resolution.
Abstract: A digital large-format long-distance micro-particle image velocimetry system (μ-PIV) was developed to measure the wall-shear-stress and the near-wall flow properties in a laminar, transitional and turbulent boundary layer flow along a flat plate, non-intrusively with high accuracy and spatial resolution. To achieve the desired measurement accuracy and spatial resolution, all experimental limitations associated with the seeding, light-sheet, out-of-focus particles, optical aberrations and distortions were successfully solved and various spatial correlation image analysis approaches based on the two-point or single-pixel ensemble correlation were developed, analyzed and compared with the state-of-the-art spatial correlation techniques. The instrument is well suited to prove fundamental fluid mechanical hypotheses such as the universality of the constants κ and B of the logarithmic law. However, for the analysis of flows at large Reynolds and Mach numbers, where small spatial dimensions and strong flow gradients prevent accurate measurements, this technique can be applied as well.
TL;DR: A synergy of rafting, favourable surface currents and a reduction in salinity of surface waters could allow freshwater paths to open far enough to enable continental flora and fauna to reach these and other isolated oceanic islands.
Abstract: Aim Amphibians are a model group for studies of the biogeographical origins of salt-intolerant taxa on oceanic islands. We used the Gulf of Guinea islands to explore the biogeographical origins of island endemism of one species of frog, and used this to gain insights into potential colonization mechanisms.
Location Sao Tome and Principe, two of the four major islands in the Gulf of Guinea, West Africa, are truly oceanic and have an exceptionally high biodiversity.
Methods Mitochondrial DNA is used to test the endemic status of a frog from Sao Tome and compare it with congeneric taxa from tropical Africa. Existing data on surface currents, surface salinity, atmospheric circulation and bird migration in the Gulf of Guinea are summarized to address hypotheses concerning colonization mechanisms.
Results The endemic status of Ptychadena newtoni (Bocage) is supported here by mitochondrial DNA sequences, and analysis of this and other molecular data indicates that an East African species close to Ptychadena mascareniensis (Dumeril and Bibron) is its nearest relative. We refute the possibility that this population was anthropogenically introduced, in favour of a natural dispersal mechanism.
Main conclusions With six endemic frogs and one caecilian, the Gulf of Guinea islands harbour a diverse amphibian fauna. Five of these species appear to have their closest relatives in East Africa. Insufficient evidence exists for transportation by storms, birds or rafts alone. However, we propose a synergy of rafting, favourable surface currents and a reduction in salinity of surface waters. Catastrophic events, or wet periods in climatic history, could allow freshwater paths to open far enough to enable continental flora and fauna to reach these and other isolated oceanic islands.
TL;DR: In this paper, an omnidirectional mirror for the terahertz range made from polypropylene and high-resistivity silicon is presented. But the structure is characterized by time-domain spectroscopy and the experimental data are in good agreement with transfer matrix calculations.
Abstract: We present an omnidirectional mirror for the terahertz range made from polypropylene and high-resistivity silicon. The structure is characterized by time-domain terahertz spectroscopy. The experimental data are in good agreement with transfer matrix calculations. In the frequency band between 319 and 375GHz the mirror is highly reflecting for all incidence angles and s as well as p polarization.
01 Jan 2006
TL;DR: It is demonstrated that the phosphate regulon is involved in the transcriptional activation of rhlR and the augmentation of PQS and pyocyanin production under phosphate limitation, but there is also an enhancement ofrhlR transcription under low-iron medium conditions and after the addition of PZS that was independent of the phosphate regulate.
Abstract: The expression of virulence determinants in Pseudomonas aeruginosa is coordinately regulated in response to both the social environment--commonly referred to as quorum sensing--and to environmental cues. In this study we have dissected the various independent regulation levels for pyocyanin production, which is influenced by the homoserine lactone- and Pseudomonas quinolone signal (PQS)-mediated quorum-sensing systems as well as by iron and phosphate availability. We demonstrate that the phosphate regulon is involved in the transcriptional activation of rhlR and the augmentation of PQS and pyocyanin production under phosphate limitation. However, we also observed an enhancement of rhlR transcription under low-iron medium conditions and after the addition of PQS that was independent of the phosphate regulon. These results highlight the complexity of secondary metabolite production in P. aeruginosa via environmental cues and the quorum-sensing system.
TL;DR: In this article, the authors analyzed the roughness of successively developed armor layers in a large laboratory flume considering gravel surfaces as two-dimensional random fields of bed elevations.
Abstract: [1] Roughness of successively developed armor layers in a large laboratory flume is analyzed considering gravel surfaces as two-dimensional random fields of bed elevations. Statistically derived roughness parameters are evaluated from precise digital elevation models (DEMs) of bed surfaces and are discussed with respect to successive development of stable armor layers. The key results relate to evolution of the probability distribution of bed elevations and its moments and structure functions of various orders with respect to armoring discharge. Our results suggest that statistical analysis of bed elevations is a helpful tool for defining roughness parameters, quantifying armoring effects, and identifying particle orientation, flow direction, and surface-forming processes.