Phases of supersymmetric O(N) theories

We perform a global renormalization group study of O(N) symmetric Wess-Zumino theories and their phases in three euclidean dimensions. At infinite N the theory is solved exactly. The phases and phase transitions are worked out for finite and infinite short-distance cutoffs. A distinctive new feature arises at strong coupling, where the effective superfield potential becomes multi-valued, signalled by divergences in the fermion-boson interaction. Our findings resolve the long-standing puzzle about the occurrence of degenerate O(N) symmetric phases. At finite N, we find a strongly-coupled fixed point in the local potential approximation and explain its impact on the phase transition. We also examine the possibility for a supersymmetric Bardeen-Moshe-Bander phenomenon, and relate our findings with the spontaneous breaking of supersymmetry in other models.Comment: 23 pages, 18 figure

Systematic Analysis of Language Transcripts Solutions: A Tutorial

Purpose: In the early 1980s, researchers and speech-language pathologists (SLPs) collaborated to develop the Systematic Analysis of Language Transcripts (SALT). Research and development over the ensuing decades has culminated into SALT Solutions, a set of tools to assist SLPs to efficiently complete language sample analysis (LSA) with their clients. In this tutorial, we describe how SALT can assist with the accurate identification of children with language disorders and provide a rich description of children\u27s functional language use. After summarizing the multiple elicitation methods developed by the SALT team, we provide case studies, showing how to select an elicitation method that aligns with a child\u27s characteristics. We then summarize major considerations when transcribing, analyzing, and interpreting language samples with SALT. We revisit our case studies to illustrate how SALT adds value to the comprehensive assessment of language in children. Conclusions: LSA is a powerful assessment tool for children suspected of having language disorders. The SALT suite of solutions provides a toolkit to assist SLPs with their comprehensive language assessments

A note on density correlations in the half-filled Hubbard model

We consider density-density correlations in the one-dimensional Hubbard model at half filling. On intuitive grounds one might expect them to exhibit an exponential decay. However, as has been noted recently, this is not obvious from the Bethe Ansatz/conformal field theory (BA/CFT) approach. We show that by supplementing the BA/CFT analysis with simple symmetry arguments one can easily prove that correlations of the lattice density operators decay exponentially.Comment: 3 pages, RevTe

Ordered phase and phase transitions in the three-dimensional generalized six-state clock model

We study the three-dimensional generalized six-state clock model at values of the energy parameters, at which the system is considered to have the same behavior as the stacked triangular antiferromagnetic Ising model and the three-state antiferromagnetic Potts model. First, we investigate ordered phases by using the Monte Carlo twist method (MCTM). We confirmed the existence of an incompletely ordered phase (IOP1) at intermediate temperature, besides the completely ordered phase (COP) at low-temperature. In this intermediate phase, two neighboring states of the six-state model mix, while one of them is selected in the low temperature phase. We examine the fluctuation the mixing rate of the two states in IOP1 and clarify that the mixing rate is very stable around 1:1. The high temperature phase transition is investigated by using non-equilibrium relaxation method (NERM). We estimate the critical exponents beta=0.34(1) and nu=0.66(4). These values are consistent with the 3D-XY universality class. The low temperature phase transition is found to be of first-order by using MCTM and the finite-size-scaling analysis

Optical conductivity of the half-filled Hubbard chain

We combine well-controlled analytical and numerical methods to determine the optical conductivity of the one-dimensional Mott-Hubbard insulator at zero temperature. A dynamical density-matrix renormalization group method provides the entire absorption spectrum for all but very small coupling strengths. In this limit we calculate the conductivity analytically using exact field-theoretical methods. Above the Lieb-Wu gap the conductivity exhibits a characteristic square-root increase. For small to moderate interactions, a sharp maximum occurs just above the gap. For larger interactions, another weak feature becomes visible around the middle of the absorption band.Comment: 4 pages with 3 eps figures, published version (changes in text and references

Dynamical density correlation function of 1D Mott insulators in a magnetic field

We consider the one dimensional (1D) extended Hubbard model at half filling in the presence of a magnetic field. Using field theory techniques we calculate the dynamical density-density correlation function $\chi_{nn}(\omega,q)$ in the low-energy limit. When excitons are formed, a singularity appears in $\chi_{nn}(\omega,q)$ at a particular energy and momentum transfer.Comment: 7 pages, 4 figure

Bodenerosionsminderung in bergigen Regionen am Beispiel des Landkreises Mansfeld-Südharz - BebeR

Die Auswirkungen des Klimawandels werden derzeit intensiv erforscht. Dabei werden insbesondere auch für die Böden Veränderungen prognostiziert, die weitreichende ökonomische, soziale und ökologische Folgen haben werden. Dabei wird eine Zunahme der Erosionsproblematik aufgrund von Starkniederschlägen und aufgrund der Veränderungen im Bodenwasser- und Stoffhaushalt prognostiziert. Vor allem bestimmen aber Landnutzung, Bodenbearbeitung und -bei ackerbaulicher Nutzung- die Wahl der Feldfrucht über das Ausmaß der Erosion. Besonders der zunehmende Versiegelungsgrad führt langfristig dazu, dass weniger Wasser versickert und mehr oberflächlicher Abfluss entsteht. In den Regionen des Mittelgebirges und deren Vorländern spielen daher sowohl die flächenhafte Erosion als auch die Gewässerbetterosion eine große Rolle. Maßnahmen zur Minderung der Erosion sind bereits in Handbüchern und Beratungsleitfäden veröffentlicht worden. In der Praxis werden diese Lösungen jedoch selten gesamtheitlich und unter Einbeziehung verschiedener Akteure durchgeführt. Ziel des Projektes ist es daher zu demonstrieren, wie ein Planungs- und Abwägungsprozess zur Minderung der Bodenerosion (Flächen- und Gewässerbetterosion) unter Einbeziehung unterschiedlicher Akteursgruppen (Kommune, Bevölkerung, Landwirtschaft, Naturschutz) im vorrangig ländlichen Raum in einer bergigen Region im Südharz (Sachsen-Anhalt) erfolgen kann. Hierbei fugiert das Gebiet um den Regenbeek, mit einer hauptsächlich gewässerbettbezogenen Erosion und der Bereich des Vietzbach, welcher von flächenhafter Erosion betroffen ist, als Beispielregion. Vor allem am Regenbeek wird deutlich, dass die vom Oberlieger durch zunehmende Versiegelung verursache erhöhte Abflussmenge, zu massiven Erosionen führt. Diese wirken sich auf den Unterlieger in Form von größeren Schlammablagerungen aus. Im BebeR-Projekt sollen vereinfachte Methoden entwickelt werden, mit denen die Erosion abgeschätzt und auf deren Grundlage Anpassungsmaßnahmen in Zusammenarbeit der Akteure aus verschiedenen Bereichen entworfen und bewertet werden

Characterization of the Modular Design of the Autolysin/Adhesin Aaa from Staphylococcus Aureus

BACKGROUND: Staphylococcus aureus is a frequent cause of serious and life-threatening infections, such as endocarditis, osteomyelitis, pneumonia, and sepsis. Its adherence to various host structures is crucial for the establishment of diseases. Adherence may be mediated by a variety of adhesins, among them the autolysin/adhesins Atl and Aaa. Aaa is composed of three N-terminal repeated sequences homologous to a lysin motif (LysM) that can confer cell wall attachment and a C-terminally located cysteine, histidine-dependent amidohydrolase/peptidase (CHAP) domain having bacteriolytic activity in many proteins. METHODOLOGY/PRINCIPAL FINDINGS: Here, we show by surface plasmon resonance that the LysM domain binds to fibrinogen, fibronectin, and vitronectin respresenting a novel adhesive function for this domain. Moreover, we demonstrated that the CHAP domain not only mediates the bacteriolytic activity, but also adherence to fibrinogen, fibronectin, and vitronectin, thus demonstrating for the first time an adhesive function for this domain. Adherence of an S. aureus aaa mutant and the complemented aaa mutant is slightly decreased and increased, respectively, to vitronectin, but not to fibrinogen and fibronectin, which might at least in part result from an increased expression of atl in the aaa mutant. Furthermore, an S. aureus atl mutant that showed enhanced adherence to fibrinogen, fibronectin, and endothelial cells also demonstrated increased aaa expression and production of Aaa. Thus, the redundant functions of Aaa and Atl might at least in part be interchangeable. Lastly, RT-PCR and zymographic analysis revealed that aaa is negatively regulated by the global virulence gene regulators agr and SarA. CONCLUSIONS/SIGNIFICANCE: We identified novel functions for two widely distributed protein domains, LysM and CHAP, i.e. the adherence to the extracellular matrix proteins fibrinogen, fibronectin, and vitronectin. The adhesive properties of Aaa might promote S. aureus colonization of host extracellular matrix and tissue, suggesting a role for Aaa in the pathogenesis of S. aureus infections