Luttinger liquid universality in the time evolution after an interaction quench

We provide strong evidence that the relaxation dynamics of one-dimensional, metallic Fermi systems resulting out of an abrupt amplitude change of the two-particle interaction has aspects which are universal in the Luttinger liquid sense: The leading long-time behavior of certain observables is described by universal functions of the equilibrium Luttinger liquid parameter and the renormalized velocity. We analytically derive those functions for the Tomonaga-Luttinger model and verify our hypothesis of universality by considering spinless lattice fermions within the framework of the density matrix renormalization group

Two-particle irreducible functional renormalization group schemes---a comparative study

We derive functional renormalization group schemes for Fermi systems which are based on the two-particle irreducible approach to the quantum many-body problem. In a first step, the cutoff is introduced in the non-interacting propagator as it is commonly done in functional renormalization group based on one-particle irreducible vertex functions. The most natural truncation of the resulting infinite hierarchy of flow equations is shown to be fully equivalent to self-consistent perturbation theory. An earlier suggested alternative truncation strategy is considered as well. In a second step, the cutoff is introduced in the two-particle interaction. Again two truncation procedures are investigated, one of which was derived before. In the latter, the mean-field solution of the many-body problem is considered as the starting point of the renormalization group flow. We compare the performance and the required numerical resources for solving the coupled flow equations for all the approximate schemes by applying them to the problem of the quantum anharmonic oscillator. In a functional integral representation, this model has a formal similarity to the quantum many-body problem. The perspectives for applying the derived two-particle irreducible functional renormalization group approaches to zero- and one-dimensional systems of correlated fermions are discussed.Comment: 32 pages, 6 figures (9 plots

Pratiques évaluatives :: de la correction à la notation

Notre travail de mémoire traite du thème de l'évaluation en septième et huitième année HarmoS et plus particulièrement des pratiques des enseignants lors de l'acte correctif. La correction est une phase où l'enseignant interprète des données et effectue des choix. Comment l'enseignant s'y prend-il concrètement? Quels facteurs peuvent influencer ses décisions? Pour répondre à ces questions, quatre enseignants exerçant dans le canton du Jura en septième ou huitième année ont participé à nos recherches par le biais d'une auto-explicitation. En effet, lors de la correction d'une évaluation sommative de mathématiques, ils ont verbalisé et précisé leurs actes, leurs choix, ainsi que leurs ressentis et leurs émotions. À travers l'analyse de ces enregistrements, nous avons tout d'abord fait l'inventaire et comparé les différentes pratiques lors de la correction. Puis, à la lecture des propos des enseignants, nous avons dégagé différents éléments (biais évaluatifs, arrangements) qui auraient tendance à influencer plus ou moins fortement le jugement du correcteur

Patients with Borderline Personality Disorder Not Participating in an RCT: Are They Different?

Background: Despite the notion that randomized controlled trials are regarded as the gold standard in psychotherapy research, questions about their generalizability have been raised. This paper focuses on the differences between participants and eligible nonparticipants of a randomized controlled trial for patients with borderline personality disorder (BPD). Sampling and Methods: One hundred forty-two patients were screened, and 122 were found eligible for study participation. Out of these, 64 patients (52.5%) gave informed consent and were included in the study. Results: The 58 eligible nonparticipants showed a lower level of functioning (global assessment of functioning score), had a history of more outpatient treatment attempts and were living alone more often. Regarding acute symptoms and severity of BPD as indexed by suicide attempts, inpatient treatments, substance abuse and history of trauma, no differences between the groups could be detected. Moreover, participants showed significantly more eating disorders, whereas nonparticipants presented more affective and anxiety disorders. Conclusions: The results indicate that lower psychosocial functioning and comorbid affective and anxiety disorders decrease BPD patients' willingness to participate in an RCT. Copyright (C) 2010 S. Karger AG, Base

ON THE EMERGENCE OF SHADOW IT - A TRANSACTION COST-BASED APPROACH

Information Technology (IT) used for business processes is not only provided by the organization´s IT department. Business departments and users autonomously implement IT solutions, which are not embedded in the organizational IT service management. This increasingly occurring phenomenon is called Shadow IT. The various opportunities and risks of Shadow IT challenge organizations and call for approaches to manage the phenomenon. An initial point to achieve measurable indications for the management is to explain why Shadow IT emerges. Therefore, this paper explores the business decision to implement Shadow IT. Based on existing research we derive that Shadow IT is created after a make-or-buy decision, which is substantiated in the Transaction Cost Theory. We deploy a triangulation approach using the methods expert interviews and multiple-case study to investigate Shadow IT emergence. Our findings identify prohibitive transaction costs in the exchange relation between business and IT departments, influnced by misalignment, as the main explanation. We conclude that the principles of Transaction Cost Theory may be applied to develop governance structures for managing Shadow IT. This strengthens the link between IT Governance and Business IT Alignment and expands the understanding of business integration within the IT domains of an organization

Observation of the phononic Lamb shift with a synthetic vacuum

The quantum vacuum fundamentally alters the properties of embedded particles. In contrast to classical empty space, it allows for creation and annihilation of excitations. For trapped particles this leads to a change in the energy spectrum, known as Lamb shift. Here, we engineer a synthetic vacuum building on the unique properties of ultracold atomic gas mixtures. This system makes it possible to combine high-precision spectroscopy with the ability of switching between empty space and quantum vacuum. We observe the phononic Lamb shift, an intruiguing many-body effect orginally conjectured in the context of solid state physics. Our study therefore opens up new avenues for high-precision benchmarking of non-trivial theoretical predictions in the realm of the quantum vacuum

Zerebrale Manifestationen bei angioneurotischem Ödem

Es wird über zwei Patienten mit familiärem angioneurotischen Ödem berichtet. Eine 1929 geborene Patientin wies einen computertomographisch gesicherten Infarkt im Bereich der A. cerebri posterior rechts auf, der 20jährige Sohn kam wegen einer transitorischen ischämischen Attacke sowie eines prolongierten reversiblen Insultes, jeweils im Gebiet der A. cerebri media links, in neurologische Behandlung. Ätiologie, klinische Symptomatik, Therapie und Differentialdiagnose cerebraler Störungen beim angioneurotischen Ödem werden im Zusammenhang mit den bisher in der Literatur beschriebenen Fällen diskutiert