Organized Current Patterns in Disordered Conductors

We present a general theory of current deviations in straight current carrying wires with random imperfections, which quantitatively explains the recent observations of organized patterns of magnetic field corrugations above micron-scale evaporated wires. These patterns originate from the most efficient electron scattering by Fourier components of the wire imperfections with wavefronts along the $\pm 45^{\circ}$ direction. We show that long range effects of surface or bulk corrugations are suppressed for narrow wires or wires having an electrically anisotropic resistivity

Shot noise in the chaotic-to-regular crossover regime

We investigate the shot noise for phase-coherent quantum transport in the chaotic-to-regular crossover regime. Employing the Modular Recursive Green's Function Method for both ballistic and disordered two-dimensional cavities we find the Fano factor and the transmission eigenvalue distribution for regular systems to be surprisingly similar to those for chaotic systems. We argue that in the case of regular dynamics in the cavity, diffraction at the lead openings is the dominant source of shot noise. We also explore the onset of the crossover from quantum to classical transport and develop a quasi-classical transport model for shot noise suppression which agrees with the numerical quantum data.Comment: 4 pages, 3 figures, submitted to Phys.Rev.Let

Large-scale albuminuria screen for nephropathy models in chemically induced mouse mutants

Background/Aim: Phenotype-driven screening of a great pool of randomly mutant mice and subsequent selection of animals showing symptoms equivalent to human kidney diseases may result in the generation of novel suitable models for the study of the pathomechanisms and the identification of genes involved in kidney dysfunction. Methods: We carried out a large-scale analysis of ethylnitrosourea (ENU)-induced mouse mutants for albuminuria by using qualitative SDS-polyacrylamide gel electrophoresis. Results: The primary albuminuria screen preceded the comprehensive phenotypic mutation analysis in a part of the mice of the Munich ENU project to avoid loss of mutant animals as a consequence of prolonged suffering from severe nephropathy. The primary screen detected six confirmed phenotypic variants in 2,011 G1 animals screened for dominant mutations and no variant in 48 G3 pedigrees screened for recessive mutations. Further breeding experiments resulted in two lines showing a low phenotypic penetrance of albuminuria. The secondary albuminuria screen was carried out in mutant lines which were established in the Munich ENU project without preceding primary albuminuria analysis. Two lines showing increased plasma urea levels were chosen to clarify if severe kidney lesions are involved in the abnormal phenotype. This analysis revealed severe albuminuria in mice which are affected by a recessive mutation leading to increased plasma urea and cholesterol levels. Conclusion: Thus, the phenotypic selection of ENU-induced mutants according to the parameter proteinuria in principle demonstrates the feasibility to identify nephropathy phenotypes in ENU-mutagenized mice. Copyright (C) 2005 S. Karger AG, Basel

Long-Range Order in Electronic Transport through Disordered Metal Films

Ultracold atom magnetic field microscopy enables the probing of current flow patterns in planar structures with unprecedented sensitivity. In polycrystalline metal (gold) films we observe long-range correlations forming organized patterns oriented at +/- 45 deg relative to the mean current flow, even at room temperature and at length scales orders of magnitude larger than the diffusion length or the grain size. The preference to form patterns at these angles is a direct consequence of universal scattering properties at defects. The observed amplitude of the current direction fluctuations scales inversely to that expected from the relative thickness variations, the grain size and the defect concentration, all determined independently by standard methods. This indicates that ultracold atom magnetometry enables new insight into the interplay between disorder and transport

Editorial: The Vascular Niche in Tissue Repair: A Therapeutic Target for Regeneration.

Editorial on the Research Topic The Vascular Niche in Tissue Repair: A Therapeutic Target for Regeneration In mammals, although regeneration is quite restricted to a number of tissues and organs, this particular healing process is possible through the existence of tissue-resident stem/progenitor cells. Upon injury, these cells are activated, they proliferate, migrate, and differentiate into tissue-specific cells and functionally replace the damaged or lost cells. Besides this, angiogenesis and neovascularization play crucial roles in tissue repair. Blood vessels (BV) together with the resident surrounding cells create a vascular niche which is central to local and distant signaling thereby shaping the regenerative response. The Frontiers Research Topic “The Vascular Niche in Tissue Repair: A Therapeutic Target for Regeneration” encompasses 14 articles highlighting various aspects of the vascular niche (VN) in health and disease. This research topic first describes ex vivo methodological aspects to study the role of the VN in regeneration, second addresses the VN cellular composition and roles during regeneration, third described local as well as distant signaling mechanisms regulating the VN in regeneration and, finally addresses the VN responses in pathology

Spontaner und posttherapeutischer Knorpelrepair: Bewertungskriterien

Zusammenfassung: Der für das Funktionieren der großen Gelenke entscheidende Gelenkknorpel besitzt beim Erwachsenen praktische keine Reparaturkapazität, weshalb einmal entstandene Schäden chronisch erhalten bleiben und sich zumeist sogar ausbreiten und in eine Osteoarthrose überzugehen drohen. Seit einem Jahrzehnt sind verschiedene neue und innovative Therapien entwickelt worden, um Regenerate zu implantieren oder intraartikulär zu induzieren und deren Funktionalität und Belastbarkeit zu erhöhen. Ein wesentlicher Parameter zur Erfassung der Funktionalität der erzeugten Regenerate ist hierbei das morphologisch erfassbare Bild, da dieses im Moment am ehesten erlaubt, Vorraussagen über die Funktionalität und Haltbarkeit der Regenerate zu treffen. Um die vielerorts laufenden Studien international vergleichend auswertbar zu machen, wurde eine Konsensusbeurteilungsskala durch die ICRS (International Cartilage Repair Society) kürzlich veröffentlicht, welche in diesem Übersichtsartikel vorgestellt und erläutert wir

Spectral Orbits and Peak-to-Average Power Ratio of Boolean Functions with respect to the {I,H,N}^n Transform

We enumerate the inequivalent self-dual additive codes over GF(4) of blocklength n, thereby extending the sequence A090899 in The On-Line Encyclopedia of Integer Sequences from n = 9 to n = 12. These codes have a well-known interpretation as quantum codes. They can also be represented by graphs, where a simple graph operation generates the orbits of equivalent codes. We highlight the regularity and structure of some graphs that correspond to codes with high distance. The codes can also be interpreted as quadratic Boolean functions, where inequivalence takes on a spectral meaning. In this context we define PAR_IHN, peak-to-average power ratio with respect to the {I,H,N}^n transform set. We prove that PAR_IHN of a Boolean function is equivalent to the the size of the maximum independent set over the associated orbit of graphs. Finally we propose a construction technique to generate Boolean functions with low PAR_IHN and algebraic degree higher than 2.Comment: Presented at Sequences and Their Applications, SETA'04, Seoul, South Korea, October 2004. 17 pages, 10 figure