Der Einfluss von Anreizsystemen auf die intrinsische Motivation

Der Einfluss unterschiedlicher Anreiztypen auf die intrinsische Motivation ist seit Jahren Gegenstand einer heftigen Kontroverse. Der vorliegende Beitrag erweitert diese Diskussion, indem er die Analyse auf zwei weitere Kernelemente von Anreizsystemen, die Ausgestaltung der Bemessungsgrundlage und der Belohnungsfunktion, ausweitet. Er arbeitet auf Basis eines sach-analytischen Vorgehens unter Einbeziehung der Theorie der kognitiven Bewertung heraus, welchen Einfluss die in der betriebswirtschaftlichen Literatur diskutierten Anforderungskriterien an diese Elemente auf die intrinsische Motivation entfalten können. Es wird ein hypothetisches Wirkungsgefüge herausgearbeitet, welches daraufhin deutet, dass ein Großteil der Anforderungskriterien positiv auf die intrinsische Motivation wirkt, und das konkrete Ansatzpunkte für weitere empirische Studien liefert.The relationship between extrinsic incentives and intrinsic motivation has attracted much debate over the last decades. Most of the extant literature focuses on the effect of different types of incentives, particularly the role of monetary rewards for intrinsic motivation. This paper adds an additional perspective to the discussion. Using cognitive evaluation theory it explores how different characteristics of incentive systems, such as the objectivity of performance assessment - as opposed to different types of incentives - affect intrinsic motivation. The analysis suggests that most of these characteristics have a positive effect on intrinsic motivation and provides detailed starting points for further empirical research

Temperature dependence of the superconducting gap anisotropy in Bi2_{2}Sr2_{2}Ca1_{1}Cu2_{2}O8+x_{8+x}

We present the first detailed data of the momentum-resolved, temperature dependence of the superconducting gap of $Bi_{2}Sr_{2}Ca_{1}Cu_{2}O_{8+x}$, complemented by similar data on the intensity of the photoemission superconducting condensate spectral area. The gap anisotropy between the $\Gamma-\bar{M}$ and $\Gamma-X$ directions increases markedly with increasing temperature, contrary to what happens for conventional anisotropic-gap superconductors such as lead. Specifically, the size of the superconducting gap along the $\Gamma-X$ direction decreases to values indistinguishable from zero at temperatures for which the gap retains virtually full value along the $\Gamma-\bar{M}$ direction.Comment: APS_REVTEX. 19 pages, including 8 figures, available upon request. UW-Madison preprin

Observation of a van Hove Singularity in Bi2Sr2Ca1Cu2O8+xBi_{2}Sr_{2}Ca_{1}Cu_{2}O_{8+x} with Angle Resolved Photoemission

We have performed high energy resolution angle-resolved photoemission studies of the normal state band structure of oxygen overdoped $Bi_{2}Sr_{2}Ca_{1}Cu_{2}O_{8+x}$. We find that there is an extended saddle point singularity in the density of states along $\Gamma-\bar{M}-Z$ direction. The data also indicate that there is an asymmetry in the Fermi surface for both the $\Gamma-\bar{M}-Z$ and perpendicular directions.Comment: APS_Revtex. 28 pages, including 16 figures, available upon request. UW-Madison preprint#

Coherent phonon dynamics at the martensitic phase transition of Ni_2MnGa

We use time-resolved optical reflectivity to study the laser stimulated dynamics in the magnetic shape memory alloy Ni_2MnGa. We observe two coherent optical phonons, at 1.2 THz in the martensite phase and at 0.7 THz in the pre-martensite phase, which we interpret as a zone-folded acoustic phonon and a heavily damped amplitudon respectively. In the martensite phase the martensitic phase transition can be induced by a fs laser pulse on a timescale of a few ps.Comment: 3 figure

Localization Effects in Bi2Sr2Ca(Cu,Co)2O8+y High Temperature Superconductors

Doping Bi2Sr2Ca1Cu2O8+y with Co causes a superconductor-insulator transition. We study correlations between changes in the electrical resistivity RHOab(T) and the electronic bandstructure using identical single crystalline samples. For undoped samples the resistivity is linear in temperature and has a vanishing residual resistivity. In angle resolved photoemission these samples show dispersing band-like states. Co-doping decreases TC and causes and increase in the residual resistivity. Above a threshold Co-concentration the resistivity is metallic (drab/dT >0) at room temperature, turns insulating below a characteristic temperature Tmin and becomes super- conducting at even lower temperature. These changes in the resistivity correlate with the disappearance of the dispersing band-like states in angle resolved photoemission. We show that Anderson localization caused by the impurity potential of the doped Co-atoms provides a consistent explanation of all experimental features. Therefore the TC reduction in 3d-metal doped high- temperature superconductors is not caused by Abrikosov Gor'kov pair- breaking but by spatial localization of the carriers. The observed suppression of TC indicates that the system is in the homogenous limit of the superconductor-insulator transition. The coexistance of insulating (dRHOab/dT <0) normal state behavior and super- conductivity indicates that the superconducting ground state is formed out of spatially almost localized carriers.Comment: Postscript file 11 pages plus 4 figures available on reques

Localized electronic states and photoemission superconducting condensate in Bi2_{2}Sr2_{2}Ca1_{1}Cu2_{2}O8+x_{8+x}

We present the first detailed angle-resolved photoemission evidence that there are two types of carriers that contribute to the photoemission superconducting condensate in $Bi_{2}Sr_{2}Ca_{1}Cu_{2}O_{8+x}$. Our data indicate that both itinerant and somewhat localized normal state carriers can contribute to the formation of Cooper pairs.Comment: APS_Revtex, 11 pages, including 3 figures, available upon request. UW-Madison preprint#

INTERLAYER COUPLING AND THE METAL-INSULATOR TRANSITION IN Pr-SUBSTITUTED Bi(2)Sr(2)CaCu(2)O(8+y)

Substitution of rare-earth ions for Ca in Bi2Sr2CaCu2O8+y is known to cause a metal-insulator transition. Using resonant photoemission we study how this chemical substitution affects the electronic structure of the material. For the partial Cu-density of states at E_F and in the region of the valence band we observe no significant difference between a pure superconducting sample and an insulating sample with 60% Pr for Ca. This suggests that the states responsible for superconductivity are predomi- nately O-states. The partial Pr-4f density of states was extracted utilizing the Super- Koster-Kronig Pr 4d-4f resonance. It consists of a single peak at 1.36eV binding energy. The peak shows a strongly assymetric Doniach-Sunjic line- shape indicating the presence of a continuum of electronic states with sharp cut off at E_F even in this insulating sample. This finding excludes a bandgap in the insulating sample and supports the existance of a mobility gap caused by spatial localization of the carriers. The presence of such carriers at the Pr-site, between the CuO_2 planes shows that the electronic structure is not purely 2-dimensional but that there is a finite interlayer coupling. The resonance enhancement of the photoemission cross section, at the Pr-4d threshold, was studied for the Pr-4f and for Cu-states. Both the Pr-4f and the Cu-states show a Fano-like resonance. This resonance of Cu-states with Pr-states is another indication of coupling between the the Pr-states and those in the CuO_2 plane. Because of the statistical distribution of the Pr-ions this coupling leads to a non-periodic potential for the states in the CuO_2 plane which can lead to localization and thus to the observed metal-insulator transition.Comment: Gziped uuencoded postscript file including 7 figures Scheduled for publication in Physical Review B, May 1, 1995

An Innovative Optical Sensor for the Online Monitoring and Control of Biomass Concentration in a Membrane Bioreactor System for Lactic Acid Production

Citation: Fan, R.; Ebrahimi, M.; Quitmann, H.; Aden, M.; Czermak, P. An Innovative Optical Sensor for the Online Monitoring and Control of Biomass Concentration in a Membrane Bioreactor System for Lactic Acid Production. Sensors 2016, 16, 411.Accurate real-time process control is necessary to increase process efficiency, and optical sensors offer a competitive solution because they provide diverse system information in a noninvasive manner. We used an innovative scattered light sensor for the online monitoring of biomass during lactic acid production in a membrane bioreactor system because biomass determines productivity in this type of process. The upper limit of the measurement range in fermentation broth containing Bacillus coagulans was ~2.2 g·L?1. The specific cell growth rate (µ) during the exponential phase was calculated using data representing the linear range (cell density ? 0.5 g·L?1). The results were consistently and reproducibly more accurate than offline measurements of optical density and cell dry weight, because more data were gathered in real-time over a shorter duration. Furthermore, µmax was measured under different filtration conditions (transmembrane pressure 0.3–1.2 bar, crossflow velocity 0.5–1.5 m·s?1), showing that energy input had no significant impact on cell growth. Cell density was monitored using the sensor during filtration and was maintained at a constant level by feeding with glucose according to the fermentation kinetics. Our novel sensor is therefore suitable for integration into control strategies for continuous fermentation in membrane bioreactor systems

Explaining parent-child (dis)agreement in generic and short stature-specific health-related quality of life reports: do family and social relationships matter?

Background: In the context of health-related quality of life (HrQoL) assessment in pediatric short stature, the present study aimed to examine the levels of agreement/disagreement between parents’ and children’s reports of generic and condition-specific HrQoL, and to identify socio-demographic, clinical and psychosocial variables associated with the extent and direction of parent-child discrepancies. Methods: This study was part of the retest phase of the QoLISSY project, which was a multicenter study conducted simultaneously in France, Germany, Spain, Sweden and UK. The sample comprised 137 dyads of children/adolescents between 8 and 18 years of age, diagnosed with growth hormone deficiency (GHD) or idiopathic short stature (ISS), and one of their parents. The participants completed child- and parent-reported questionnaires on generic (KIDSCREEN-10 Index) and condition-specific HrQoL (QoLISSY Core Module). Children/adolescents also reported on social support (Oslo 3-items Social Support Scale) and parents assessed the parent-child relationships (Parental Role subscale of the Social Adjustment Scale) and burden of short stature on parents (QoLISSY- additional module). Results: The parent-child agreement on reported HrQoL was strong (intraclass correlation coefficients between .59 and .80). The rates of parent-child discrepancies were 61.5 % for generic and 35.2 % for condition-specific HrQoL, with the parents being more prone to report lower generic (42.3 %) and condition-specific HrQoL (23.7 %) than their children. The extent of discrepancies was better explained by family and social relationships than by clinical and socio-demographic variables: poorer parent-child relationships and better children’s social support were associated with larger discrepancies in generic HrQoL, while more parental burden was associated with larger discrepancies in condition-specific HrQoL reports. Regarding the direction of discrepancies, higher parental burden was significantly associated with parents’ underrating, and better children’s social support was significantly associated with parents’ overrating of condition-specific HrQoL. Conclusions: Routine assessment of pediatric HrQoL in healthcare and research contexts should include child- and parent-reported data as complementary sources of information, and also consider the family and social context.This study is part of the “Quality of Life in Short Stature Youth” (QoLISSY) project, a joint initiative between the University Medical Centre Hamburg-Eppendorf and ©Pfizer Limited