Interference in interacting quantum dots with spin

We study spectral and transport properties of interacting quantum dots with spin. Two particular model systems are investigated: Lateral multilevel and two parallel quantum dots. In both cases different paths through the system can give rise to interference. We demonstrate that this strengthens the multilevel Kondo effect for which a simple two-stage mechanism is proposed. In parallel dots we show under which conditions the peak of an interference-induced orbital Kondo effect can be split.Comment: 8 pages, 8 figure

Intraossäre Infusionstechnik

Zusammenfassung: Die intraossäre Infusionstechnik ist zum festen Bestandteil in der pädiatrischen aber auch adulten Notfallmedizin geworden und gehört heute zu den wichtigsten Fertigkeiten eines Notarztes, Pädiaters, Anästhesisten und Intensivmediziners. Die intraossäre Infusionstechnik ist eine sichere, zuverlässige und schnelle Methode, um bei Kindern unter 6Jahren mit Kreislaufstillstand oder schwerem hypovolämischem Schock primär und beim vital gefährdeten Kind mit schwierigen Venenverhältnissen sekundär einen Gefäßzugang zu legen. Auf diesem Weg können alle in der Notfallmedizin intravenös verabreichten Medikamente und Flüssigkeiten nahezu uneingeschränkt, im Vergleich zur intravenösen Gabe in äquivalenter Dosierung und mit vergleichbaren Anschlagszeiten appliziert werden. Kenntnisse über Indikationen, Punktionsstellen, Material, Technik, Vorsichtsmaßnahmen und Komplikationen sowie Training am Übungsknochen sind wichtig für den sicheren und erfolgreichen klinischen Einsatz. Bei richtiger Indikationsstellung gibt es abgesehen von lokalen Gründen wie Frakturen, voroperierter Knochen oder kürzlich vorausgegangene Punktionsversuche sowie Durchblutungsstörungen der betroffenen Extremität keine absoluten Kontraindikationen für eine intraossäre Infusion. Komplikationen sind bei richtiger Anwendung und Handhabung extrem selten und das Risiko steht in keinem Verhältnis zu den Vorteilen einer intraossären Infusion beim vital bedrohten Patiente

Soft repulsive mixtures under gravity: brazil-nut effect, depletion bubbles, boundary layering, nonequilibrium shaking

A binary mixture of particles interacting via long-ranged repulsive forces is studied in gravity by computer simulation and theory. The more repulsive A-particles create a depletion zone of less repulsive B-particles around them reminiscent to a bubble. Applying Archimedes' principle effectively to this bubble, an A-particle can be lifted in a fluid background of B-particles. This "depletion bubble" mechanism explains and predicts a brazil-nut effect where the heavier A-particles float on top of the lighter B-particles. It also implies an effective attraction of an A-particle towards a hard container bottom wall which leads to boundary layering of A-particles. Additionally, we have studied a periodic inversion of gravity causing perpetual mutual penetration of the mixture in a slit geometry. In this nonequilibrium case of time-dependent gravity, the boundary layering persists. Our results are based on computer simulations and density functional theory of a two-dimensional binary mixture of colloidal repulsive dipoles. The predicted effects also occur for other long-ranged repulsive interactions and in three spatial dimensions. They are therefore verifiable in settling experiments on dipolar or charged colloidal mixtures as well as in charged granulates and dusty plasmas.Comment: 10 pages, 11 figure

Different aprotinin applications influencing hemostatic chances in orthotopic liver transplantation

The effect of different aprotinin applications on hemmtatic changes and blood product requirements in orthotopic liver transplantation was investigated in a prospective, open, and randomized study. From November 1989 to June 1990, 13 patients received aprotinin as a bolus of 0.5 Mill, kallikrein inac-tivator units (KIU) on three occasions in the course of an OLT, whereas 10 other patients were treated with continuous aprotinin infusion of 0.1-0.4 Mill. KIU/hr. Before and after reperfusion of the graft liver, signs of hyperfibrinolysis, measured by thrombelastography, were significantly lower in the infusion group. Tissue-type plasminogen activator (t-PA) activity increased during the anhepatic phase but to a significantly lesser extent in the infusion group. Blood product requirements during OLT were tendentiously higher in the bolus group but not significantly so. However, the use of packed red blood cells was significantly lower in the postoperative period, whereas there was no significant difference in fresh frozen plasma requirements between the two groups. All 23 patients have survived, and only one woman of each group required retransplantation due to severe host-versus-graft reactions. Furthermore, we investigated the perfusate of the graft liver in both groups and detected signs of a decreased t-PA release in the infusion group. Our results demonstrate an advantage of aprotinin given as continuous infusion over bolus application in OLT

Active control of the aerodynamic performance and tonal noise of axial turbomachines

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Two projects on axial fans are presented in this paper. The first aims at improving the aerodynamic performance and reducing the tip clearance noise caused by the rotating instability. This is achieved by injecting air into the radial gap between the impeller blade tips and the fan casing. Steady air injection with small mass flows results in remarkable reductions in the noise level along with improved aerodynamic performance. Larger injected mass flows give significant improvements in the aerodynamic performance at the expense of an increased overall noise level. The second project uses flow control actively to reduce the blade passage frequency (BPF) level. Experimental results are presented for steady jets injected into the main flow and cylindrical rods at axial positions downstream of the impeller blades. The method is successful for higher-order mode sound fields where the BPF level is reduced by up to 20.5 dB.DFB, SFB 557, Beeinflussung komplexer turbulenter Scherströmunge

Thickness-dependent secondary structure formation of tubelike polymers

By means of sophisticated Monte Carlo methods, we investigate the conformational phase diagram of a simple model for flexible polymers with explicit thickness. The thickness constraint, which is introduced geometrically via the global radius of curvature of a polymer conformation, accounts for the excluded volume of the polymer and induces cooperative effects supporting the formation of secondary structures. In our detailed analysis of the temperature and thickness dependence of the conformational behavior for classes of short tubelike polymers, we find that known secondary-structure segments like helices and turns, but also ringlike conformations and stiff rods are dominant intrinsic topologies governing the phase behavior of such cooperative tubelike objects. This shows that the thickness constraint is indeed a fundamental physical parameter that allows for a classification of generic polymer structures

Kinderanästhesie zur Protonenbestrahlung: Medizin fernab der Klinik

Zusammenfassung: Die Betreuung von Kleinkindern für die Protonentherapie stellt fachlich und menschlich hohe Anforderungen an das Anästhesieteam. Das Anästhesiepersonal soll in Kinderanästhesie speziell ausgebildet und erfahren sein, insbesondere da die Kinder sich oft in einem reduzierten Allgemeinzustand befinden. Die Infrastruktur soll gemäß den aktuellen anästhesiologischen Standards eingerichtet sein. Die ständige visuelle Überwachung des sedierten Patienten und das lückenlose Monitoring der Vitaldaten müssen gewährleistet sein. Propofol eignet sich ideal für die Sedierung von Kleinkindern in Spontanatmung für die Protonentherapie. Auch bei repetitiver Gabe über mehrere Wochen wird Propofol sehr gut toleriert. Eine enge Zusammenarbeit zwischen Radioonkologe, Onkologe und Anästhesist ist notwendig, um interkurrent auftretende medizinische Probleme optimal zu behandeln. Die besonderen Belange onkologischer Patienten müssen bei der Therapieplanung berücksichtigt werde