Critical properties of the metal-insulator transition in anisotropic systems

We study the three-dimensional Anderson model of localization with anisotropic hopping, i.e., weakly coupled chains and weakly coupled planes. In our extensive numerical study we identify and characterize the metal-insulator transition by means of the transfer-matrix method. The values of the critical disorder $W_c$ obtained are consistent with results of previous studies, including multifractal analysis of the wave functions and energy level statistics. $W_c$ decreases from its isotropic value with a power law as a function of anisotropy. Using high accuracy data for large system sizes we estimate the critical exponent as $\nu=1.62\pm0.07$. This is in agreement with its value in the isotropic case and in other models of the orthogonal universality class.Comment: 17 pages, 7 figures, requires svjour.csl and svepj.clo (included), submitted to EPJ

Essays on the effects of deferred taxation and tax audit negotiations

This dissertation contains a total of three papers. In the first two studies, behavioral economic effects resulting from deferred taxation are examined. The last study deals with the question which factors influence the choice of negotiation strategies of tax auditors of the tax authorities and which effects these strategies have on the outcome of a tax audit. The first study uses several laboratory experiments to show that taxes are misperceived when savings decisions are made in a deferred taxation system. This leads to significantly lower after-tax pensions than in an economically equivalent system of immediate taxation. For subjects with low tax and financial knowledge, the misperceptions remain despite accumulated experience. For all subjects, the tax misperceptions almost disappear only after they have received recurrent numerical informational nudges regarding pension taxation and have gained experience. Furthermore, using government matching contributions instead of tax deductions might reduce necessary informational costs and still achieve significantly higher retirement savings. The second study shows that deferred income taxation influences not only individual saving behavior but also entrepreneurs' production behavior and risk allocation. Several laboratory experiments reveal that nearly 80\% of all subjects engage in overproduction. This is mainly due to the fact that subjects underweight the deferred tax burden because they often act myopically and tend to make decisions in isolation rather than simultaneously (choice bracketing). As a result, the willingness to take risks decreases. This is particularly due to the additional cognitive load associated with the taxation of investment income. However, the participants learn through experience. Despite these learning effects, however, the overproduction is only marginally reduced, since mainly participants with high cognitive capacity learn. Overproduction and distortions in risk allocation only almost disappear if the timing of taxation is changed from a deferred to an economically equivalent immediate taxation system. For the last paper of this dissertation, German tax auditors were asked about their negotiation strategies in connection with the outcome of a tax audit. The study shows that the outcome and the probability of agreement during an audit depend on which negotiation strategy the tax auditor chooses. Furthermore, the study provides insights into the determinants of the auditor's choice of strategy. It is shown that the choice of strategy is influenced not only by tax auditor's audit experience, the availability of higher authority, time pressure or the quality of a taxpayer's financial accounting system but also by the perceived negotiation strategy of the tax advisor.Diese Dissertation beinhaltet insgesamt drei Beiträge. In den ersten beiden Beiträgen werden verhaltensökonomische Effekte infolge einer nachgelagerten Besteuerung untersucht. Der letzte Beitrag widmet sich der Frage, welche Faktoren Steuerprüfer der Finanzverwaltung bei der Wahl der Verhandlungsstrategie beeinflussen und welche Effekte diese Strategien auf das Ergebnis einer Steuerprüfung haben. Die erste Studie zeigt mithilfe mehrerer Laborexperimente, dass Steuern bei Sparentscheidungen in einem nachgelagerten Besteuerungssystem verzerrt wahrgenommen werden. Dies führt zu wesentlich geringeren Renten nach Steuern als bei einem ökonomisch äquivalenten System der sofortigen bzw. vorgelagerten Besteuerung. Dieses Ergebnis deutet auf substantielle Steuerfehlwahrnehmungen bei der nachgelagerten Besteuerung hin. Für Individuen mit geringem Steuer- und Finanzwissen bleiben die Verzerrungen trotz gesammelter Erfahrung bestehen. Die steuerlichen Fehleinschätzungen verschwinden bei allen Individuen erst dann nahezu, wenn sie wiederkehrende numerische Informationen zur Rentenbesteuerung erhalten und Erfahrung gesammelt haben. Weiterhin können staatliche Zulagen die Nachsteuerrenten über das Niveau der sofortigen Besteuerung anheben, ohne dass zusätzliche steuerliche Informationen bereitgestellt werden. Die zweite Studie belegt, dass die nachgelagerte Einkommensbesteuerung nicht nur das individuelle Sparverhalten, sondern auch das Produktionsverhalten von Unternehmern und die Risikoallokation beeinflusst. In mehreren Laborexperimenten wird deutlich, dass die nachgelagerte Besteuerung bei 80 \% der Probanden zu einer Überproduktion führt. Ein wesentlicher Grund hierfür ist, dass Probanden die nachgelagerte Steuerlast zu gering gewichten, weil sie oft myopisch handeln und dazu neigen, Entscheidungen eher isoliert als gleichzeitig zu treffen (choice bracketing). Infolgedessen sinkt die Risikobereitschaft. Dies ist besonders auf die zusätzliche kognitive Belastung im Zusammenhang mit der Besteuerung von Investitionsrückflüssen zurückzuführen. Die Probanden lernen jedoch durch Erfahrung, wobei sich die Überproduktion nur marginal verringert, da hauptsächlich die Probanden mit hoher kognitiver Kapazität lernen. Nur wenn der Besteuerungszeitpunkt von einem nachgelagerten zu einem wirtschaftlich äquivalenten sofortigen Besteuerungssystem geändert wird, verschwinden die Überproduktion und die Verzerrungen bei der Risikoallokation nahezu vollständig. Für den letzten Beitrag dieser Dissertation wurden deutsche Steuerprüfer zu ihren Verhandlungsstrategien im Zusammenhang mit dem Ergebnis einer Steuerprüfung befragt. Die Studie zeigt, dass das Ergebnis und die Einigungswahrscheinlichkeit beider Parteien einer Prüfung davon abhängen, welche Verhandlungsstrategie der Steuerprüfer wählt. Weiterhin gibt die Studie über die Determinanten der Strategiewahl eines Prüfers Aufschluss. Danach wird die Wahl der Strategie neben der Berufserfahrung, dem Zeitdruck eines Prüfers oder der Qualität des Finanzbuchhaltungssystems eines Steuerzahlers auch durch die wahrgenommene Verhandlungsstrategie des Steuerberaters beeinflusst

Interaction dynamics between heterotrimeric G-proteins and type V adenylyl cyclase determine sensitivity of effector regulation

The signalling pathway from G-protein-coupled receptors to the second messenger cAMP is present in virtually all cells and of major physiological and pathophysiological importance. The membrane-spanning receptors can easily be targeted by pharmaceutical compounds and therapies to treat diseases like hypertension, asthma or pain affect cellular cAMP-levels. Biochemical studies have revealed a lot of important information about the interaction of the proteins participating in this signalling cascade, namely the receptors, the G-proteins and adenylyl cyclases. The development of new microscopic methods allowed to dynamically investigate protein/protein-interactions. While these techniques have already been widely used to investigate in vivo signalling dynamics of the receptors, G-proteins and second messengers, research on adenylyl cyclases (ACs) mainly relied on in vitro methods or steady-state interaction studies. An assay, based on Förster Resonance Energy Transfer (FRET), was developed within this study, to investigate the dynamic interaction between G-proteins and ACs in living cells, thereby providing a platform for biochemical analysis in vivo. Furthermore, a protocol was established to resolve Gi protein-mediated regulation of cAMP in single living cells by means of FRET. For the assays, a fluorescently labelled AC5 was cloned. Bioluminescence-based cAMP measurements proved the constructs wild-type-like functionality with respect to stimulation through forskolin and Gs-proteins. The new protocol for FRET-based cAMP measurements verified Gs- and Gi-protein signalling competence of the labelled AC5. The new assay was used to analyse agonist-dependent interaction between AC5 and Gαs-, Gαi1- and Gβ1γ2-subunits, respectively. Although no basal interaction between the G-protein subunits and AC5 was observed, all subunits showed an increase in FRET upon agonist-stimulation of the according receptors. Interestingly, the different combinations of AC5 and G-protein subunits showed distinct FRET-signals. The agonist-dependent Gβ1γ2/AC5-FRET increase and decrease followed an exponential course, closely resembling other FRET-signals observed for G-proteins. FRET between Gαs and AC5 was characterised by a transient peak in the onset of the signal. Contrastingly, Gαi1 and AC5 showed an additional transient increase in their FRET-signal upon agonist withdrawal. The signal-phenotypes observed between Gα-subunits and AC5 possibly indicate additional conformational changes within the G-protein/AC5 complex. The onset-kinetics of the interaction between AC5 and G-protein-subunits were fast and in the same range as previously observed G-protein activation-kinetics. The interaction between Gαi1 and AC5 was found to be especially sensitive and proved to be left-shifted in comparison to the activation of the Gi1-protein itself. Downstream events of Gi-dependent regulation of AC5 and Gi-protein activity further verified this difference on a functional level. Gi-dependent inhibition of AC5-regulated cAMP levels was determined with the newly established protocol for the FRET-based cAMP sensor Epac1-camps. In comparison to GIRK currents, which reflect Gi1 protein activity, the receptor-induced Gi-protein-mediated inhibition of stimulated AC5 activity was shifted by two orders of magnitude. This was in line with previous reports on higher sensitivity of cAMP-involving over Gi-protein activity-dependent pathways. After appropriate controls ruled out confounding mechanisms that could shift the apparent sensitivity of the assay, the interaction kinetics between AC5 and Gαi1 remained as a major contributing cause. Indeed the interaction of Gαi1-subunits with AC5 was prolonged in comparison to the deactivation of the Gi1-protein and could not be accelerated by RGS4. This indicates a slow dissociation of AC5 and Gαi1, which prevents the deactivation and reassembly of the Gi1 protein, thereby affecting the dynamics of the G-protein cycle. Presumably, the balance in the G protein cycle between inactive and active G-proteins is shifted towards a higher amount of AC5-bound active G-proteins, providing the putative molecular mechanism for the high sensitivity observed in the interaction studies

Nutritional characterization of gluten free non-traditional pasta

When a food is formulated, its characterization is important from the chemical and biochemical point of view; even more whennon-traditional raw materials are used. Noodles were made with cassava starch and corn flour (4:1), milk, egg, salt and xanthangum. The chemical composition of the pasta was determined and the total and resistant starch content was quantified. Thehydrolysis rate of the starch was measured at different times, from which the hydrolysis index and, subsequently, the predictiveglycemic index was calculated. The chemical composition of the noodles showed its high content of total fibers. From thedigestibility tests, high values were obtained for proteins (93%), and average values for the starch (52%). The results of the starchhydrolysis kinetics showed a higher proportion of slowly digestible starch with a low glycemic index (46%). Analyzed noodles arewithin the dietary guidelines that suggest a diet with high total dietary fiber content and low glycemic index.Fil: Milde, Laura Beatríz. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Chigal, Paola Soledad. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Chiola Zayas, Maria Ofelia. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales; Argentin

Scaling law and critical exponent for alpha_0 at the 3D Anderson transition

We use high-precision, large system-size wave function data to analyse the scaling properties of the multifractal spectra around the disorder-induced three-dimensional Anderson transition in order to extract the critical exponents of the transition. Using a previously suggested scaling law, we find that the critical exponent is significantly larger than suggested by previous results. We speculate that this discrepancy is due to the use of an oversimplified scaling relation