Diffusive Josephson junctions made out of multiwalled carbon nanotubes

We have investigated electrical transport in diffusive multiwalled carbon nanotubes (MWNT) contacted using superconducting leads made of Ti/Al/Ti sandwich structure. We measure proximity-induced supercurrents up to Icm = 1.3 nA and find tunability by the gate voltage due to variation of the Thouless energy via the diffusion constant that is controlled by scattering in the MWNT. The modeling of these results by long, diffusive SNS junctions, supplemented with phase diffusion effects is discussed: the agreement between theory and experiments is tested especially on the basis of the temperature dependence of the Josephson coupling energy. In order to prove conclusively that the diffusive model works for MWNT proximity junctions, we propose an improved measurement scheme that is based on the kinetic inductance of superconducting junctions.Peer reviewe

Duality-invariant Quantum Field Theories of Charges and Monopoles

We present a manifestly Lorentz- and SO(2)-Duality-invariant local Quantum Field Theory of electric charges, Dirac magnetic monopoles and dyons. The manifest invariances are achieved by means of the PST-mechanism. The dynamics for classical point particles is described by an action functional living on a circle, if the Dirac-Schwinger quantization condition for electric and magnetic charges holds. The inconsistent classical field theory depends on an arbitrary, but fixed, external vector field, a generalization of the Dirac-string. Nevertheless, the Quantum Field Theory, obtained from this classical action via a functional integral approach, turns out to be independent of the particular vector field chosen, and thus consistent, if the Dirac-Schwinger quantization condition holds. We provide explicit expressions for the generating functionals of observables, proving that they are Dirac-string independent. Since Lorentz-invariance is manifest at each step, the quantum theory admits also a manifestly diffeomorphism invariant coupling to external gravity. Relations with previous formulations, and with SO(2)--non invariant theories are clarified.Comment: 49 pages, LaTeX, no figure

An Early Reduction in Treg Cells Correlates with Enhanced Local Inflammation in Cutaneous Leishmaniasis in CCR6-Deficient Mice

Resistance to Leishmania major infection is dependent on the development of a cell-mediated Th1 immune response in resistant C57BL/6 mice whereas Th2-prone BALB/c mice develop non-healing lesions after infection. The chemokine receptor CCR6 is shared by anti-inflammatory regulatory T cells and pro-inflammatory Th17 cells. In a recent study we showed that C57BL/6 mice deficient in CCR6 exhibited enhanced footpad swelling and impaired T helper cell migration indicated by reduced recruitment of total T helper cells into the skin after infection and a reduced delayed type hypersensitivity reaction. Based on these findings we tested whether the lack of CCR6 alters Treg or Th17 cell responses during the course of Leishmania major infection. When we analyzed T cell subsets in the lymph nodes of CCR6-deficient mice, Th17 cell numbers were not different. However, reduced numbers of Treg cells paralleled with a stronger IFNγ response. Furthermore, the early increase in IFNγ-producing cells correlated with increased local tissue inflammation at later time points. Our data indicate an important role of CCR6 for Treg cells and a redundant role for Th17 cells in a Th1 cell-driven anti-parasitic immune response against Leishmania major parasites in resistant C57BL/6 mice

Wedge-Local Quantum Fields and Noncommutative Minkowski Space

Within the setting of a recently proposed model of quantum fields on noncommutative Minkowski spacetime, the consequences of the consistent application of the proper, untwisted Poincare group as the symmetry group are investigated. The emergent model contains an infinite family of fields which are labelled by different noncommutativity parameters, and related to each other by Lorentz transformations. The relative localization properties of these fields are investigated, and it is shown that to each field one can assign a wedge-shaped localization region of Minkowski space. This assignment is consistent with the principles of covariance and locality, i.e. fields localized in spacelike separated wedges commute. Regarding the model as a non-local, but wedge-local, quantum field theory on ordinary (commutative) Minkowski spacetime, it is possible to determine two-particle S-matrix elements, which turn out to be non-trivial. Some partial negative results concerning the existence of observables with sharper localization properties are also obtained.Comment: Version to appear in JHEP, 27 page

EIT ground-state cooling of long ion strings

Electromagnetically-induced-transparency (EIT) cooling is a ground-state cooling technique for trapped particles. EIT offers a broader cooling range in frequency space compared to more established methods. In this work, we experimentally investigate EIT cooling in strings of trapped atomic ions. In strings of up to 18 ions, we demonstrate simultaneous ground state cooling of all radial modes in under 1 ms. This is a particularly important capability in view of emerging quantum simulation experiments with large numbers of trapped ions. Our analysis of the EIT cooling dynamics is based on a novel technique enabling single-shot measurements of phonon numbers, by rapid adiabatic passage on a vibrational sideband of a narrow transition

Die Nutzung der Innovationsdaten des Mannheimer Innovationspanels für die Politikberatung

Die Daten des Mannheimer Innovationspanels (MIP), einer großen Befragung zum Innovationsverhalten deutscher Unternehmen, stellen eine qualitativ hochwertige Basis für die Politikberatung dar. Der Beitrag zeigt auf, wie die Daten und Ergebnisse der jährlichen Erhebung konkret für die Politikberatung genutzt werden. Ein erster Schritt ist die Berichterstattung zum Status quo und zu aktuellen Entwicklungen. Die Ergebnisse der seit 1993 durchgeführten Erhebung fließen unter anderem in Berichte an Ministerien, Publikationen der Europäischen Union, Beiträge für Fachzeitschriften und die Tagespresse ein. Darüber hinaus werden die Daten des Mannheimer Innovationspanels in großem Umfang wissenschaftlich ausgewertet. Themen für wissenschaftliche Analysen mit innovationspolitischer Relevanz sind zum Beispiel der Einfluss von Innovation auf Beschäftigung und Produktivität und die Evaluation von Forschungs- und Technologiepolitik. Der Beitrag endet mit einem Beispiel für die Evaluation öffentlicher Forschungs- und Entwicklungsförderung in Deutschland und Flandern. Das Beispiel zeigt, wie wissenschaftliche Analysen mit Politikberatung verknüpft werden können.The Mannheim Innovation Panel (MIP), a large scale survey on innovation activities of German firms, is a high-quality database that can be used for policy analysis and policy advice. The article describes how the data from the annual surveys are used for policy advice. A first aspect is the standard reporting on the status quo and developments: The survey's results are included in reports to German ministries, in European Commission publications, specialised journals and newspaper articles. In addition, the data is used for scientific analysis. Topics related to policy issues are for example, the effects of innovation on productivity and employment or the evaluation of public programs for R&D and innovation. The article concludes with an example of an evaluation of R&D funding in Germany and Flanders, which shows how scientific analysis and policy advice can be linked

Ultraviolet singularities in classical brane theory

We construct for the first time an energy-momentum tensor for the electromagnetic field of a p-brane in arbitrary dimensions, entailing finite energy-momentum integrals. The construction relies on distribution theory and is based on a Lorentz-invariant regularization, followed by the subtraction of divergent and finite counterterms supported on the brane. The resulting energy-momentum tensor turns out to be uniquely determined. We perform the construction explicitly for a generic flat brane. For a brane in arbitrary motion our approach provides a new paradigm for the derivation of the, otherwise divergent, self-force of the brane. The so derived self-force is automatically finite and guarantees, by construction, energy-momentum conservation.Comment: 41 pages, no figures, minor change