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In groupware tools, the activation of a function may affect other users who might have conflicting interests. We developed technical mechanisms to support users in resolving them. Contrary to current implementations of groupware tools, these mechanisms strengthen the position of the users who are affected by the activation of said functions. Supporting the visibility of a function's activation, and providing a channel for communication or means to intervene against the function's activation are approaches which constitute a framework to implement these mechanisms. We conclude with showing implementation examples of the framework and their evaluation in the POLITeam project. 相似文献
74.
Sustainable management of acidic mining lakes requires knowledge on the origin and reactivity of its sedimentary organic matter. We identified different pools of organic matter (OM) in the Fe-rich sediment (up to 35 wt %) of an acidic (pH 2.8) mining lake using delta13C-signals, C/N ratios, and the markers alkanes, lignin-derived phenols, and benzenepolycarboxylic acids (BPCA). Additionally, a density fractionation was applied to each sediment layer. Three fractions, aquatic (AOM), terrestrial (TOM), and lignite-derived (LOM) organic matter, were discriminated, of which AOM comprises only a small fraction, with a minimum at the sediment bottom. The terrestrial contribution to sedimentary OM is higher than that of AOM but still low throughout the sediment core, whereas lignite-derived OM constitutes the major C-fraction, even in the upper sediment layers. The size of the carbon pools was quantified with a mass-balance approach, in which the BPCA content was utilized as an estimate for the lignite fraction in combination with the delta13C-signals of the three C fractions. The largest amount of OM was found in the heaviest (>2.4 g cm3) of the three density fractions of the two upper sediment layers, which implies strong interaction with iron hydroxides. Comparisons with C-oxidation rates revealed that besides the refractory origin of the OM, sorptive preservation by solid iron phases controls C-reactivity in the sediment and, hence, the internal neutralization capacity of the lake system. 相似文献
75.
For agriculturally used areas, which are contaminated by the debris from a nuclear accident, the use of chemical amendmends (e.g. potassium chloride and lime) is among the most common soil-based countermeasures. These countermeasures are intended to reduce the plant uptake of radionuclides (mainly 137Cs and 90Sr) by competitive inhibition by chemically similar ions. So far, the impacts of countermeasures on soil solution composition - and thus, their effectiveness - have almost exclusively been established experimentally, since they depend on mineral composition and chemical characteristics of the soil affected. In this study, which focuses on caesium contamination, the well-established code PHREEQC was used as a geochemical model to calculate the changes in the ionic compositions of soil solutions, which result from the application of potassium or ammonium in batch equilibrium experiments. The simple ion exchange model used by PHREEQC was improved by taking into account selective sorption of Cs+, NH4+ and K+ by clay minerals. Calculations were performed with three different initial soil solution compositions, corresponding to particular soil types (loam, sand, peat). For loamy and sandy soils, our calculational results agree well with experimental data reported by Nisbet (Effectiveness of soil-based countermeasures six months and one year after contamination of five diverse soil types with caesium-134 and strontium-90. Contract Report NRPB-M546, National Radiation Protection Board, Chilton, 1995.). For peat, discrepancies were found indicating that for organic soils a reliable set of exchange constants of the relevant cations still has to be determined experimentally. For cesium, however, these discrepancies almost disappeared if selective sites were assumed to be inaccessible. Additionally, results of sensitivity analyses are presented by which the influence of the main soil parameters on Cs+ concentrations in solution after soil treatment has been systematically studied. It is shown that calculating the impacts of soil-based chemical countermeasures on soil solution chemistry using geochemical codes such as PHREEQC offers an attractive alternative to establishing these impacts by often time-consuming and site-specific experiments. 相似文献
76.
Klocke V 《Journal of nanoscience and nanotechnology》2002,2(3-4):435-440
In recent years Klocke Nanotechnik and partners have developed a new Nanorobotics system that builds a bridge between nanotechnology and classical mechanical engineering. These products combine the advantages of the two technologies: the backlash-free movement of up to 2 kg of load over a stroke of up to 70 mm with a resolution of a few nanometers. This series of positioning modules offers numerous degrees of freedom in the smallest volume for microassembly, interconnection technology, analysis, and reliability testing. Integrated position sensors allow automatic usage, also in rough production technology applications. The repeatability of classical assembly lines is limited to a few microns. Nanorobotics modules allow absolute positioning within 50 nm. 相似文献
77.
Egelhofer V Gobom J Seitz H Giavalisco P Lehrach H Nordhoff E 《Analytical chemistry》2002,74(8):1760-1771
A new strategy for identifying proteins by MALDI-TOF-MS peptide mapping is reported. In contrast to current approaches, the strategy does not rely on a good relative or absolute mass accuracy as the criterion that discriminates false positive results. The protein sequence database is first searched for all proteins that match a minimum five of the submitted masses within the maximum expected relative errors when the default or externally determined calibration constants are used, for instance, +/-500 ppm. Typically, this search retrieves many thousand candidate sequences. Assuming initially that each of these is the correct protein, the relative errors of the matching peptide masses are calculated for each candidate sequence. Linear regression analysis is then performed of the calculated relative errors as a function of m/z for each candidate sequence, and the standard deviation to the regression is used to distinguish the correct sequence among the candidates. We show that this parameter is independent of whether the mass spectrometric data were internally or externally calibrated. The result is a search engine that renders internal spectrum calibration unnecessary and adapts to the quality of the raw data without user interference. This is made possible by a dynamic scoring algorithm, which takes into account the number of matching peptide masses, the percentage of the protein's sequence covered by these peptides and, as new parameter, the determined standard deviation. The lower the standard deviation, the less cleavage peptides are required for identification and vice versa. Performance of the new strategy is demonstrated and discussed. All necessary computing has been implemented in a computer program, free access to which is provided in the Internet. 相似文献
78.
Process-Centered Software Engineering Environments, A Brief History and Future Challenges 总被引:3,自引:0,他引:3
Volker Gruhn 《Annals of Software Engineering》2002,14(1-4):363-382
Software engineering environments have a history of about two decades. Early environments provided support for small fragments of the software process (usually focusing on programming-in-the small). Then there was a trend towards support for more complete software processes (from early phases like requirements analysis and design down to testing and configuration management). Ten years ago the notion of process-centered software engineering environments initiated a new field in software engineering: software process research. The key idea is to use a model of a software process as input parameter for a software engineering environment. The environment is supposed to behave in accordance to the process model. Some aspects of this vision became true, others turned out to be of little practicability. In this article, we discuss the history of software engineering environments with a particular focus on process-centered software engineering environments (PCSEEs). We discuss the notion of distributed software processes (as one of the most substantial current trends in software process research) and we motivate the notion of a software process middleware which serves as basis of real-world software processes spread over various sites. In addition, we discuss some other trends in the software process research arena. 相似文献
79.
Volker Willert Julian Eggert Jürgen Adamy Raphael Stahl Edgar K?rner 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2006,36(5):982-994
This paper proposes a biologically inspired and technically implemented sound localization system to robustly estimate the position of a sound source in the frontal azimuthal half-plane. For localization, binaural cues are extracted using cochleagrams generated by a cochlear model that serve as input to the system. The basic idea of the model is to separately measure interaural time differences and interaural level differences for a number of frequencies and process these measurements as a whole. This leads to two-dimensional frequency versus time-delay representations of binaural cues, so-called activity maps. A probabilistic evaluation is presented to estimate the position of a sound source over time based on these activity maps. Learned reference maps for different azimuthal positions are integrated into the computation to gain time-dependent discrete conditional probabilities. At every timestep these probabilities are combined over frequencies and binaural cues to estimate the sound source position. In addition, they are propagated over time to improve position estimation. This leads to a system that is able to localize audible signals, for example human speech signals, even in reverberating environments. 相似文献
80.
Summary Polymerizable enamines were synthesized by the reaction of 2-acetoacetoxyethyl methacrylate (AAEMA) with various aliphatic mono- and diamines. The enamines were characterized by elemental analyses, IR,1H NMR and13C NMR spectroscopy. Radical polymerization of synthesized enamines yielded polymers with pendant enamine groups which were also prepared by the reaction of poly(AAEMA) with the corresponding amines. 相似文献