1,527 research outputs found
Simulating acrylate polymerization reactions: Toward improved mechanistic understanding and reliable parameter estimates
No full textIt is well accepted that free-radical acrylate polymerizations are governed by a complex coupled kinetic mechanism consisting of propagation, termination and inter-molecular transfer to small species such as monomer or modifiers, together with intra- and inter-molecular transfer reactions to polymer. Propagation, P-scission or termination of the transient secondary/tertiary radicals formed following transfer to polymer is possible. This reaction cascade strongly affects the micro-structural characteristics of the polymer and its application properties. Individual parts of this mechanism have been discussed on many occasions. However, a general approach for determining the rate coefficients for the full kinetic scheme has been missing. Such an approach is developed in this communication
Changing the means of managerial work: effects of automated decision support systems on personnel selection tasks
No full textTo enhance the quality and efficiency of information processing and decision-making, automation based on artificial intelligence
and machine learning has increasingly been used to support managerial tasks and duties. In contrast to classical applications of
automation (e.g., within production or aviation), little is known about how the implementation of automation for management
changes managerial work. In a work design frame, this study investigates how different versions of automated decision support
systems for personnel selection as a specific management task affect decision task performance, time to reach a decision,
reactions to the task (e.g., enjoyment), and self-efficacy in personnel selection. In a laboratory experiment, participants (N =
122) were randomly assigned to three groups and performed five rounds of a personnel selection task. The first group received a
ranking of the applicants by an automated support system before participants processed applicant information (support-beforeprocessing group), the second group received a ranking after they processed applicant information (support-after-processing
group), and the third group received no ranking (no-support group). Results showed that satisfaction with the decision was higher
for the support-after-processing group. Furthermore, participants in this group showed a steeper increase in self-efficacy in
personnel selection compared to the other groups. This study combines human factors, management, and industrial/
organizational psychology literature and goes beyond discussions concerning effectiveness and efficiency in the emerging area
of automation in management in an attempt to stimulate research on potential effects of automation on managers’ job satisfaction
and well-being at work
Simulation as a Tool for Feasibility Studies about PIP-SEC Experiments
No full textAdvanced homo- and copolymerization models have been used to perform a feasibility study on the potential of pulse-initiated polymerization (PIP) experiments for ethene (co)polymerizations. An application of PIP experiments directly to the ethene homo-polymerization appears not as a very promising strategy to derive the homo-propagation rate coefficient k(p) of ethene. This failure can be attributed to the special characteristics of high temperature size exclusion chromatographs, being required to determine the molecular weight distribution (MWD) of polyethylene. PI copolymerizations appear as an interesting alternative to provide access to the homo-propagation rate coefficient of ethene. Most advantageous in this strategy is the fact that even a simple convergence contemplation (using a variation in monomer composition) yields the ethene home-propagation rate coefficient k(p). Simply aiming at this coefficient, there is no necessity of knowing the detailed kinetic parameters of the copolymerization. In a further part, the extended kinetic information being available about branching processes in ethene polymerizations was used to test for the potential influence of a slower propagation rate of secondary macroradicals on the PIP structure in MWDs. Even at the significant level of branching present in ethene homopolymerizations still a PLP structure inside the MWD remains observable, assuming retardation up to an extend of almost two orders of magnitude. In order to perform these studies a kinetic model was designed explicitly accounting for the formation of secondary macroradicals by transfer. The kinetic; information about branching being available in literature, was adopted toward this scheme
"... gelegentlich der Rettung und Verlagerung der Busch-Bibliothek ...". Anmerkungen zur Rückgabe der Bücherei Richard Gustav Busch
No full textThe provenance research at Vienna University Library has lead to some volumes of the library Richard Gustav Busch being located in the Theatre, Film and Media Studies Library of the University of Vienna. In 1943 the library Richard Gustav Busch arrived as a lawful loan of the city of Münster at the newly founded Central Institute for Theatre Studies of Vienna University, which was led by Heinz Kindermann. Between 1945 and 1958 the library Richard Gustav Busch was considered property of the Austrian state. Only in 1958, with the passing of the 1957 treaty between the Republic of Austria and the Federal Republic of Germany concerning the regulation of relations concerning property rights ("Vertrag zwischen der Republik Österreich und der Bundesrepublik Deutschland zur Regelung vermögensrechtlicher Beziehungen" - Vermögensvertrag), the legal possibility of returning the holdings came about. The Busch library was returned in 1968. In 2010 it was complemented by the volumes found as part of the University Library's provenance research, which were also returned
Modeling Kinetics and Structural Properties in High-Pressure Fluid-Phase Polymerization
No full textThe present contribution provides an overview of actual applications in modeling free-radical polymerizations. Topics of interest are the simulation of pulsed laser polymerization experiments with subsequent analysis of the formed product by size exclusion chromatography (PLP-SEC), single pulse laser experiments, experimental techniques for determining rate coefficients of elementary reactions that control polymer properties, and technical applications. Aspects being investigated are model validation and testing predictive potential in polymerization models using well-defined experiments as well as developing and testing experimental strategies for deriving rate coefficients of elementary reactions that exist (especially when dealing with copolymerizations) within a network of complex coupled reactions, in any of these fields remarkable success in modeling can be achieved. This demonstrates the great potential that can grow from combining modem mathematical methods, computational power and detailed kinetic insights into the mechanism of polymerization It is the wide scope of applications, e.g. ranging from modeling kinetics to the investigation of termination processes being dependent on the chain-length of the macroradical (as an example of pure fundamental research) to modeling of technical reactors, that provides attractiveness and defines challenges. Especially, the success in transforming results directly from laboratory experiments into technical applications justifies laborious efforts in determining highly precise rate coefficients and proves the concept breaking down a complex process into elementary subparts. A necessary boundary condition for this is keeping in mind the demands along the whole scope of applications and avoiding simplifications that are only applicable for part of them. Although at a first glance this may appear to hinder fast progress in one discipline, it is the essential require ment for final success
Cardiovascular reactivity is independently associated with better mental health: results from the nationwide German DEGS1 study
No full textObjectiveUsing data from the nationwide German DEGS1 study, we assessed whether resting blood pressure (BP) and transient changes in BP are associated with symptoms of depression and quality of life (QoL).MethodsThe study included n=4852 adult participants not taking antihypertensives, who completed the Patient Health Questionnaire-9 for assessment of depressive symptoms and the SF-36 for assessment of QoL. Resting BP was defined as the mean of the second and third reading taken at 3-min intervals.ResultsGeneral linear models adjusting for age, sex, and BMI showed that both resting BP and short-term BP changes were associated with higher SF-36 mental component summary and lower Patient Health Questionnaire-9 scores.ConclusionOur data showed that a greater decrease in systolic BP as an indicator for cardiovascular reactivity is related to better mental QoL and fewer depressive symptoms, suggesting a link between BP regulation and mental well-being as part of an adaptive process to mild stressors
Loan supply in Germany during the financial crisis
No full textDistinguishing pure supply effects from other determinants of price and quantity in the market for loans is a notoriously difficult problem. Using German data, we employ Bayesian vector autoregressive models with sign restrictions on the impulse response functions in order to enquire the role of loan supply and monetary policy shocks for the dynamics of loans to non-financial corporations. For the three quarters following the Lehman collapse, we find very strong negative loan supply shocks, while monetary policy was essentially neutral. Nevertheless, the historical decomposition shows a cumulated negative impact of loan supply shocks and monetary policy shocks on loans to non-financial corporations, due to the lagged effects of past loan supply and monetary policy shocks. However, these negative effects on loans to non-financial corporations are overcompensated by positive other shocks, which implies that loans developed more favorably than implied by the model, over the past few quarters. --Loan supply,Bayesian VAR,sign restrictions
Chain-length dependence of free-radical termination rate deduced from laser single-pulse experiments
No full textTermination rate coefficients of free-radical polymerization are accessible from SP-PLP studies where monomer conversion induced by a laser single pulse is measured with a time resolution of microseconds. Previous experiments with 2,2-dimethoxy-2-phenylacetophenone (DMPA) acting as the initiator revealed that upon variation of the DMPA concentration, the resulting monomer conversion vs. time traces intersect. A detailed kinetic analysis of this unexpected type of behavior is presented. It turns out that such crossings occur in situations Where k(t) is chain-length dependent and, at the same time. the primary initiator-derived free-radical species differ in reactivity toward the monomer. As is known from the literature, this difference in radical reactivity is particularly pronounced with DMPA, which photo-decomposes to a propagating and to a non-propagating free radical. Modeling of the crossing behavior opens a novel route for determining chain-length dependent k(t). Results for methyl acrylate (MA) and styrene homopolymerizations at low degrees of monomer conversion, to a maximum of are presented. The decrease of k(t) with chain length is modeled via an exponential function. The dependence is significantly larger for styrene. The exponents derived from simulation studies via PREDICI® are in excellent agreement with corresponding data reported by Olaj et al. for styrene and by de Kock for methyl acrylate
Financial integration within the European Union: Towards a single market for insurance
No full textOur study analyses the extent of integration of the EU market for life and non-life insurance. The main integration indicator used is the market share (premium based) of foreign companies in domestic markets. For the calculation of this indicator, three different kinds of foreign presence are taken into account: foreign presence through merger and acquisitions, through branches and agencies and direct cross-border sales without physical presence. Whereas the static view reveals a high degree of national fragmentation the dynamic view indicates advancing integration. The results also show that integration is even less advanced for life than for non-life insurance and that mergers and acquisitions are the dominant strategy to access a foreign market. Besides summarising the liberalisation history of the European insurance sector and discussing consumer benefits from further integration, the study contributes to a better understanding of obstacles to insurance market integration.European Financial Integration; Insurance Sector; Internal Market
Supplemental_material - A Retrospective Analysis of Nonocclusive Mesenteric Ischemia in Medical and Surgical ICU Patients: Clinical Data on Demography, Clinical Signs, and Survival
No full textSupplemental_material for A Retrospective Analysis of Nonocclusive Mesenteric Ischemia in Medical and Surgical ICU Patients: Clinical Data on Demography, Clinical Signs, and Survival by Klaus Stahl, Markus Busch, Sabine K. Maschke, Andrea Schneider, Michael P. Manns, Jan Fuge, Olaf Wiesner, Bernhard C. Meyer, Marius M. Hoeper, Jan B. Hinrichs, and Sascha David in Journal of Intensive Care Medicine</p
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