85 research outputs found

    Nuclear Resonance Vibrational Spectroscopy of Iron Sulfur Proteins

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    Nuclear inelastic scattering in conjunction with density functional theory (DFT) calculations has been applied for the identification of vibrational modes of the high-spin ferric and the high-spin ferrous iron-sulfur center of a rubredoxin-type protein from the thermophylic bacterium Pyrococcus abysii

    Self-reported fatigue in patients with rheumatoid arthritis compared to patients with cancer: results from two large-scale studies

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    Fatigue is a common symptom in patients with rheumatoid arthritis (RA) and in patients with cancer (CA). The aim was to investigate the degree of fatigue in RA patients as compared to CA patients as well as potential influencing factors on RA-related fatigue. This was a retrospective analyses of two prospective cohort studies that used the EORTC QLQ-FA12 as a common instrument to assess fatigue. The cohort of RA patients was based on a nationwide survey in Germany. The cohort of CA patients was recruited in the context of an international validation field study. Multivariable ANCOVAs compared levels of fatigue between the two cohorts, also including various subgroup analyses. Regression analyses explored influencing factors on RA patients’ fatigue. Data of n = 705 RA patients and of n = 943 CA patients were available for analyses. RA patients reported significantly higher Physical Fatigue (mean difference = 7.0, 95% CI 4.2–9.7, p < 0.001) and Social Sequelae (mean difference = 7.5, 95% CI 4.7–10.2, p < 0.001). CA patients reported higher Cognitive Fatigue (mean difference = 3.5, 95% CI 1.4–5.6, p = 0.001). No differences in Emotional Fatigue (p = 0.678) and Interference with Daily Life (p = 0.098) were found. In RA patients, mental health and pain were associated with fatigue (p values < 0.001). RA patients showed a considerable level of fatigue that is comparable to and in certain cases even higher than that of CA patients. The implementation of standardized diagnostic procedures and interventions to reduce fatigue in RA patients are recommended

    M\"ossbauer, nuclear inelastic scattering and density functional studies on the second metastable state of Na2[Fe(CN)5NO]\cdot2H2O

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    The structure of the light-induced metastable state SII of Na2[Fe(CN)5NO]\cdot2H2O 14 was investigated by transmission M\"ossbauer spectroscopy (TMS) in the temperature range 15 between 85 and 135 K, nuclear inelastic scattering (NIS) at 98 K using synchrotron 16 radiation and density functional theory (DFT) calculations. The DFT and TMS results 17 strongly support the view that the NO group in SII takes a side-on molecular orientation 18 and, further, is dynamically displaced from one eclipsed, via a staggered, to a second 19 eclipsed orientation. The population conditions for generating SII are optimal for 20 measurements by TMS, yet they are modest for accumulating NIS spectra. Optimization 21 of population conditions for NIS measurements is discussed and new NIS experiments on 22 SII are proposed

    On Predicting Mössbauer Parameters of Iron-Containing Molecules with Density-Functional Theory

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    The performance of six frequently used density functional theory (DFT) methods (RPBE, OLYP, TPSS, B3LYP, B3LYP*, and TPSSh) in the prediction of Mössbauer isomer shifts(δ) and quadrupole splittings (ΔEQ) is studied for an extended and diverse set of Fe complexes. In addition to the influence of the applied density functional and the type of the basis set, the effect of the environment of the molecule, approximated with the conducting-like screening solvation model (COSMO) on the computed Mössbauer parameters, is also investigated. For the isomer shifts the COSMO-B3LYP method is found to provide accurate δ values for all 66 investigated complexes, with a mean absolute error (MAE) of 0.05 mm s–1 and a maximum deviation of 0.12 mm s–1. Obtaining accurate ΔEQ values presents a bigger challenge; however, with the selection of an appropriate DFT method, a reasonable agreement can be achieved between experiment and theory. Identifying the various chemical classes of compounds that need different treatment allowed us to construct a recipe for ΔEQ calculations; the application of this approach yields a MAE of 0.12 mm s–1 (7% error) and a maximum deviation of 0.55 mm s–1 (17% error). This accuracy should be sufficient for most chemical problems that concern Fe complexes. Furthermore, the reliability of the DFT approach is verified by extending the investigation to chemically relevant case studies which include geometric isomerism, phase transitions induced by variations of the electronic structure (e.g., spin crossover and inversion of the orbital ground state), and the description of electronically degenerate triplet and quintet states. Finally, the immense and often unexploited potential of utilizing the sign of the ΔEQ in characterizing distortions or in identifying the appropriate electronic state at the assignment of the spectral lines is also shown

    Review on computational methods for Lyapunov functions

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    Lyapunov functions are an essential tool in the stability analysis of dynamical systems, both in theory and applications. They provide sufficient conditions for the stability of equilibria or more general invariant sets, as well as for their basin of attraction. The necessity, i.e. the existence of Lyapunov functions, has been studied in converse theorems, however, they do not provide a general method to compute them. Because of their importance in stability analysis, numerous computational construction methods have been developed within the Engineering, Informatics, and Mathematics community. They cover different types of systems such as ordinary differential equations, switched systems, non-smooth systems, discrete-time systems etc., and employ di_erent methods such as series expansion, linear programming, linear matrix inequalities, collocation methods, algebraic methods, set-theoretic methods, and many others. This review brings these different methods together. First, the different types of systems, where Lyapunov functions are used, are briefly discussed. In the main part, the computational methods are presented, ordered by the type of method used to construct a Lyapunov function

    The Normative Problem of Merit Goods in Perspective

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    In his Theory of Public Finance (1959), Musgrave invented the concept of merit wants to describe public wants that are satisfied by goods provided by the government in violation of the principle of consumer sovereignty. Starting from Musgrave’s mature discussion (1987), I construct two categories to classify the explanations of merit goods. The first strand of thought attempts to justify merit goods within the New welfare economics, by modifying its assumptions to accommodate irrationality, uncertainty, lack of information, and psychic externalities. The second category encompasses more radical departures from consumer sovereignty, drawn from philosophical critiques of economics. In the third part of the paper, I argue that the two strands might be represented by a non-individualistic social welfare function. I also show how this solution echoes Musgrave’s early views on public expenditures before he coined the concept of merit wants. From an historical perspective, the survival of the concept highlights the persistence of a social point of view in welfare economics
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