Functional methods for correlation functions of integrable face and anyon models

The computation of correlation functions in models of statistical mechanics is the key to comparing theoretical results with actual measurements. In the context of integrable lattice models there exists a rich literature on correlators in vertex models and related quantum-spin chains. Less is known for integrable face models and their related anyon chains. Therefore, we define generalised transfer matrices allowing for a solution of the `inverse problem', i.e.\ we express local operators by means of objects from the Yang-Baxter algebra. This motivates the study of reduced density matrices which contain the information of all correlation functions. Instead of directly calculating them, we show that they fulfil a set of functional equations. We use these equations to study density matrices in (R)SOS models and their related anyon chains. In particular, we find integral representations for the two and three-point functions of the $r=4$ RSOS model and calculate those quantities for the $r=5$ model in the thermodynamic limit. In addition we observe a factorisation of the three-point functions into two-point functions and propose an efficient algorithm to factorise reduced density matrices for generic models. In the last section we study density matrices for the $SO(5)_2$ face models. We examine the structure of the two-site reduced density matrices and simplify them for certain topological sectors. Since there exist different inequivalent sets of Boltzmann weights, the latter is done for each choice leading to sets of discrete functional equations

KMU-Ratingmodelle und Ratingqualität: Auswirkungen der Ratingarchitektur auf die ex-ante Risikoklassifikation von KMU-Kreditkontrakten

Zusammenfassung: Aus der Sicht einer KMU als aktuelle oder potentielle Kreditnachfragerin bei einer Bank stellt sich die Frage, ob eine unterschiedliche Ausgestaltung interner Ratingmodelle verschiedener Kreditanbieter bei grundsätzlich identischen Inputdaten zu unterschiedlichen Bonitätsklassifikationen und unterschiedlichen Kreditkonditionen führt. Mit dieser Fragestellung befasst sich der vorliegende Beitrag. Sie ist unter dem Aspekt optimaler Allokationseffizienz sowohl aus makroökonomischer wie aus mikroökonomischer Sicht von Bedeutung. Wir bewerten ein für den schweizerischen KMU-Markt repräsentatives Portfolio von insgesamt 435 KMU-Kreditnehmern mit drei verschiedenen Ratingmodellen, die typisch für die bei Banken zur Bewertung von KMU-Risiken eingesetzten Modelle stehen. Dabei testen wir zunächst die Frage, ob differierende Ratingarchitekturen für den Kreditnehmer c.p. zu einem signifikant unterschiedlichen Rating führen. Diese Vermutung kann aufgrund der Untersuchung bestätigt werden. Anschliessend untersuchen wir die Hypothese, ob der Einbezug qualitativer Informationen zu einer signifikant höheren Bonitätseinschätzung im Vergleich zur Ratingevaluation auf der Basis rein quantitativer Informationen führt. Diese Hypothese muss verworfen werden, was teilweise im Gegensatz zu bisherigen empirischen Erkenntnissen steh

Density matrices in integrable face models

Using the properties of the local Boltzmann weights of integrable interaction-round-a-face (IRF or face) models we express local operators in terms of generalized transfer matrices. This allows for the derivation of discrete functional equations for the reduced density matrices in inhomogeneous generalizations of these models. We apply these equations to study the density matrices for IRF models of various solid-on-solid type and quantum chains of non-Abelian $\bm{su(2)_3}$ or Fibonacci anyons. Similar as in the six vertex model we find that reduced density matrices for a sequence of consecutive sites can be 'factorized', i.e.\ expressed in terms of nearest-neighbour correlators with coefficients which are independent of the model parameters. Explicit expressions are provided for correlation functions on up to three neighbouring sites.Comment: Submission to SciPos

Factorization of density matrices in the critical RSOS models

We study reduced density matrices of the integrable critical RSOS model in a particular topological sector containing the ground state. Similar as in the spin-$1/2$ Heisenberg model correlation functions of this model on short segments can be `factorized': they are completely determined by a single nearest-neighbour two-point function $\omega$ and a set of structure functions. While $\omega$ captures the dependence on the system size and the state of the system the structure functions can be expressed in terms of the possible operators on the segment, in the present case representations of the Temperley-Lieb algebra $\text{TL}_n$, and are independent of the model parameters. We present explicit results for the function $\omega$ in the infinite system ground state of the model and compute multi-point local height probabilities for up to four adjacent sites for the RSOS model and the related three-point correlation functions of non-Abelian $su(2)_k$ anyons.Comment: 19 pages, 3 figure

Herstellung rekombinanter Vaccinia-Viren als Träger des Oberflächenproteins MSP1 aus Plasmodium falciparum und ihre Charakterisierung in Hinsicht auf einen Malaria-Impfstoff

Malaria, insbesondere die durch P. falciparum verursachte Malaria tropica ist eine der meist verbreiteten und gefährlichsten Infektionskrankheiten der Welt. Eine entscheidende Rolle zur Bekämpfung der Krankheit kommt der Impfstoffentwicklung zu. Das Hauptoberflächenprotein 1 des Merozoiten-Stadiums der Plasmodium ssp. (MSP1), welches in zwei unterschiedlichen Varianten existiert, gilt als ein vielversprechender Kandidat für die Entwicklung eines Malariaimpfstoffs. Durch die chemische Synthese des msp1f-Gens (msp1 des K1-Prototyps) aus P. falciparum in unserem Labor ist es erstmals gelungen, das Gen in seiner gesamten Länge in prokaryotischen und eukaryotischen Systemen zu klonieren und das Protein heterolog herzustellen. Im ersten Teil der Arbeit wurde die Synthese des msp1d-Gens (msp1 des MAD20-Prototyp) abgeschlossen und das Gen anschließend in E. coli kloniert und exprimiert. Der Hauptteil der Arbeit befasst sich mit der Entwicklung rekombinanter, msp1-exprimierender Vaccinia-Viren. Durch die Fusion an die Signalsequenz oder die Kombination aus Signal- und GPI-Ankersequenz des Decay Accelerating Factor (DAF) wurde MSP1 oder Teile davon in das Medium exportiert oder auf der Zelloberfläche verankert. Erste Untersuchungen zur Immunogenität im Mausmodell mit unterschiedliche Kombinationen der rekombinanten Viren untereinander und mit gereinigtem MSP1D-42 aus E. coli lieferten folgende Ergebnisse: (i) Durch rekombinante MVA induzierte, MSP1D-42-spezifische Antikörpertiter waren niedrig verglichen zur Immunisierung mit MSP1D-42 aus E. coli. (ii) Bezüglich der humoralen Immunantwort erschien verankertes MSP1D-42 immunogener als sekretiertes. (iii) Eine starke, wenn auch sehr kurzlebige, humorale Immunantwort wurde durch die Immunsierung mit einer Kombination aus Protein-Erstimmunisierung und nachfolgender Stimulation durch rekombinante MVA induziert. Einzig die Immunisierung mit MSP1D-42 aus E. coli allein lieferte langanhaltend hohe Antikörpertiter

Evidence of blood stage efficacy with a virosomal malaria vaccine in a Phase IIa clinical trial

Background Previous research indicates that a combination vaccine targeting different stages of the malaria life cycle is likely to provide the most effective malaria vaccine. This trial was the first to combine two existing vaccination strategies to produce a vaccine that induces immune responses to both the pre-erythrocytic and blood stages of the P. falciparum life cycle. Methods This was a Phase I/IIa study of a new combination malaria vaccine FFM ME-TRAP+PEV3A. PEV3A includes peptides from both the pre-erythrocytic circumsporozoite protein and the blood-stage antigen AMA-1. This study was conducted at the Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, UK. The participants were healthy, malaria naïve volunteers, from Oxford. The interventions were vaccination with PEV3A alone, or PEV3A+FFM ME-TRAP. The main outcome measure was protection from malaria in a sporozoite challenge model. Other outcomes included measures of parasite specific immune responses induced by either vaccine; and safety, assessed by collection of adverse event data. Results We observed evidence of blood stage immunity in PEV3A vaccinated volunteers, but no volunteers were completely protected from malaria. PEV3A induced high antibody titres, and antibodies bound parasites in immunofluorescence assays. Moreover, we observed boosting of the vaccine-induced immune response by sporozoite challenge. Immune responses induced by FFM ME-TRAP were unexpectedly low. The vaccines were safe, with comparable side effect profiles to previous trials. Although there was no sterile protection two major observations support an effect of the vaccine-induced response on blood stage parasites: (i) Lower rates of parasite growth were observed in volunteers vaccinated with PEV3A compared to unvaccinated controls (p = 0.012), and this was reflected in the PCR results from PEV3A vaccinated volunteers. These showed early control of parasitaemia by some volunteers in this group. One volunteer, who received PEV3A alone, was diagnosed very late, on day 20 compared to an average of 11.8 days in unvaccinated controls. (ii). Morphologically abnormal parasites were present in the blood of all (n = 24) PEV3A vaccinated volunteers, and in only 2/6 controls (p = 0.001). We describe evidence of vaccine-induced blood stage efficacy for the first time in a sporozoite challenge study

Nitrosative stress treatment of E. coli targets distinct set of thiol-containing proteins

Reactive nitrogen species (RNS) function as powerful antimicrobials in host defence, but so far little is known about their bacterial targets. In this study, we set out to identify Escherichia coli proteins with RNS-sensitive cysteines. We found that only a very select set of proteins contain cysteines that undergo reversible thiol modifications upon nitric oxide (NO) treatment in vivo . Of the 10 proteins that we identified, six (AtpA, AceF, FabB, GapA, IlvC, TufA) have been shown to harbour functionally important thiol groups and are encoded by genes that are considered essential under our growth conditions. Media supplementation studies suggested that inactivation of AceF and IlvC is, in part, responsible for the observed NO-induced growth inhibition, indicating that RNS-mediated modifications play important physiological roles. Interestingly, the majority of RNS-sensitive E. coli proteins differ from E. coli proteins that harbour H 2 O 2 -sensitive thiol groups, implying that reactive oxygen and nitrogen species affect distinct physiological processes in bacteria. We confirmed this specificity by analysing the activity of one of our target proteins, the small subunit of glutamate synthase. In vivo and in vitro activity studies confirmed that glutamate synthase rapidly inactivates upon NO treatment but is resistant towards other oxidative stressors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72397/1/j.1365-2958.2007.05964.x.pd

Proceedings of the Linux Audio Conference 2018

These proceedings contain all papers presented at the Linux Audio Conference 2018. The conference took place at c-base, Berlin, from June 7th - 10th, 2018 and was organized in cooperation with the Electronic Music Studio at TU Berlin