2,698 research outputs found
Real-Time Dynamics of Typical and Untypical States in Non-Integrable Systems
For a class of typical states, the real-time and real-space dynamics of
non-equilibrium density profiles has been recently studied for integrable
models, i.e. the spin-1/2 XXZ chain [PRB 95, 035155 (2017)] and the
Fermi-Hubbard chain [PRE 96, 020105 (2017)]. It has been found that the
non-equilibrium dynamics agrees with linear response theory. Moreover, in the
regime of strong interactions, clear signatures of diffusion have been
observed. However, this diffusive behavior strongly depends on the choice of
the initial state and disappears for untypical states without internal
randomness. In the present work, we address the question whether or not the
above findings persist for non-integrable models. As a first step, we study the
spin-1/2 XXZ chain, where integrability can be broken due to an additional
next-nearest neighbor interaction. Furthermore, we analyze the differences of
typical and untypical initial states on the basis of their entanglement and
their local density of states.Comment: 15 pages, 15 figure
In-gap features in superconducting LaAlO-SrTiO interfaces observed by tunneling spectroscopy
We identified quasiparticle states at well-defined energies inside the
superconducting gap of the electron system at the LaAlO-SrTiO interface
using tunneling spectroscopy. The states are found only in a number of samples
and depend upon the thermal-cycling history of the samples. The states consist
of a peak at zero energy and other peaks at finite energies, symmetrically
placed around zero energy. These peaks disappear, together with the
superconducting gap, with increasing temperature and magnetic field. We discuss
the likelihood of various physical mechanisms that are known to cause in-gap
states in superconductors and conclude that none of these mechanisms can easily
explain the results. The conceivable scenarios are the formation of Majorana
bound states, Andreev bound states, or the presence of an odd-frequency spin
triplet component in the superconducting order parameter.Comment: 11 pages, 5 figure
Genesis and Propagation of Fractal Structures During Photoelectrochemical Etching of n-Silicon
The genesis, propagation, and dimensions of fractal-etch patterns that form anodically on front- or back-illuminated n-Si(100) photoelectrodes in contact with 11.9 M NH₄F(aq) has been investigated during either linear-sweep voltammetry or when the electrode was held at a constant potential (E = +6.0 V versus Ag/AgCl). Optical images collected in situ during electrochemical experiments revealed the location and underlying mechanism of initiation and propagation of the structures on the surface. X-ray photoelectron spectroscopic (XPS) data collected for samples emersed from the electrolyte at varied times provided detailed information about the chemistry of the surface during fractal etching. The fractal structure was strongly influenced by the orientation of the crystalline Si sample. The etch patterns were initially generated at points along the circumference of bubbles that formed upon immersion of n-Si(100) samples in the electrolyte, most likely due to the electrochemical and electronic isolation of areas beneath bubbles. XPS data showed the presence of a tensile-stressed silicon surface throughout the etching process as well as the presence of SiO_xF_y on the surface. The two-dimensional fractal dimension D_(f,2D) of the patterns increased with etching time to a maximum observed value of D_(f,2D)=1.82. Promotion of fractal etching near etch masks that electrochemically and electronically isolated areas of the photoelectrode surface enabled the selective placement of highly branched structures at desired locations on an electrode surface
Cytoplasmic islet cell antibodies recognize distinct islet antigens in IDDM but not in stiff man syndrome
Cytoplasmic islet cell antibodies are well-established predictive markers of IDDM. Although target molecules of ICA have been suggested to be gangliosides, human monoclonal ICA of the immunoglobulin G class (MICA 1-6) produced from a patient with newly diagnosed IDDM recognized glutamate decarboxylase as a target antigen. Here we analyzed the possible heterogeneity of target antigens of ICA by subtracting the GAD-specific ICA staining from total ICA staining of sera. This was achieved 1) by preabsorption of ICA+ sera with recombinant GAD65 and/or GAD67 expressed in a baculovirus system and 2) by ICA analysis of sera on mouse pancreas, as GAD antibodies do not stain mouse islets in the immunofluorescence test. We show that 24 of 25 sera from newly diagnosed patients with IDDM recognize islet antigens besides GAD. In contrast, GAD was the only islet antigen recognized by ICA from 7 sera from patients with stiff man syndrome. Two of these sera, however, recognized antigens besides GAD in Purkinje cells. In patients with IDDM, non-GAD ICA were diverse. One group, found in 64% of the sera, stained human and mouse islets, whereas the other group of non-GAD ICA was human specific. Therefore, mouse islets distinguish two groups of non-GAD ICA and lack additional target epitopes of ICA besides GAD. Longitudinal analysis of 6 sera from nondiabetic ICA+ individuals revealed that mouse-reactive ICA may appear closer to clinical onset of IDDM in some individuals
Scaling properties of ballistic nano-transistors
Recently, we have suggested a scale-invariant model for a nano-transistor. In agreement with experiments a close-to-linear thresh-old trace was found in the calculated ID - VD-traces separating the regimes of classically allowed transport and tunneling transport. In this conference contribution, the relevant physical quantities in our model and its range of applicability are discussed in more detail. Extending the temperature range of our studies it is shown that a close-to-linear thresh-old trace results at room temperatures as well. In qualitative agreement with the experiments the ID - VG-traces for small drain voltages show thermally activated transport below the threshold gate voltage. In contrast, at large drain voltages the gate-voltage dependence is weaker. As can be expected in our relatively simple model, the theoretical drain current is larger than the experimental one by a little less than a decade
Der Deutsche Germanistenverband –: eine „Fachgenossenschaft“ im Zielkonflikt
Deutscher Germanistenverband: An Academic Association in a Conflict of Objectives
From its inauguration in 1912 until 1933 the DGV resembled an ideological society successfully pursuing anti-modern nationalistic goals in the area of educational and school policy with modern methods. At best, it might be said to have only marginally fulfilled the role of an academic association for the field of study. While it did not actively seek to join the National Socialist movement, it did not resist it either. Only since its annually held conference in966 has the DGV started to deal with its past and subsequently reformed the association’s activities rigorously to become a modern academic association. What remains problematic today, is the fact that the DGV represents both the interests of German scholars from higher education and those of school teachers of German – which in fact frequently diverge from each other – and therefore, due to internal differentiation, is in danger of being reduced to being an umbrella association
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