Excited state spectroscopy in carbon nanotube double quantum dots

We report on low temperature measurements in a fully tunable carbon nanotube double quantum dot. A new fabrication technique has been used for the top-gates in order to avoid covering the whole nanotube with an oxide layer as in previous experiments. The top-gates allow us to form single dots, control the coupling between them and we observe four-fold shell filling. We perform inelastic transport spectroscopy via the excited states in the double quantum dot, a necessary step towards the implementation of new microwave-based experiments.Comment: 16 pages, 6 figures, submitted to nanoletter

Profound effect of profiling platform and normalization strategy on detection of differentially expressed microRNAs

Adequate normalization minimizes the effects of systematic technical variations and is a prerequisite for getting meaningful biological changes. However, there is inconsistency about miRNA normalization performances and recommendations. Thus, we investigated the impact of seven different normalization methods (reference gene index, global geometric mean, quantile, invariant selection, loess, loessM, and generalized procrustes analysis) on intra- and inter-platform performance of two distinct and commonly used miRNA profiling platforms. We included data from miRNA profiling analyses derived from a hybridization-based platform (Agilent Technologies) and an RT-qPCR platform (Applied Biosystems). Furthermore, we validated a subset of miRNAs by individual RT-qPCR assays. Our analyses incorporated data from the effect of differentiation and tumor necrosis factor alpha treatment on primary human skeletal muscle cells and a murine skeletal muscle cell line. Distinct normalization methods differed in their impact on (i) standard deviations, (ii) the area under the receiver operating characteristic (ROC) curve, (iii) the similarity of differential expression. Loess, loessM, and quantile analysis were most effective in minimizing standard deviations on the Agilent and TLDA platform. Moreover, loess, loessM, invariant selection and generalized procrustes analysis increased the area under the ROC curve, a measure for the statistical performance of a test. The Jaccard index revealed that inter-platform concordance of differential expression tended to be increased by loess, loessM, quantile, and GPA normalization of AGL and TLDA data as well as RGI normalization of TLDA data. We recommend the application of loess, or loessM, and GPA normalization for miRNA Agilent arrays and qPCR cards as these normalization approaches showed to (i) effectively reduce standard deviations, (ii) increase sensitivity and accuracy of differential miRNA expression detection as well as (iii) increase inter-platform concordance. Results showed the successful adoption of loessM and generalized procrustes analysis to one-color miRNA profiling experiments

Spin-dependent electronic hybridization in a rope of carbon nanotubes

We demonstrate single electron addition to different strands of a carbon nanotube rope. Anticrossings of anomalous conductance peaks occur in quantum transport measurements through the parallel quantum dots forming on the individual strands. We determine the magnitude and the sign of the hybridization as well as the Coulomb interaction between the carbon nanotube quantum dots, finding that the bonding states dominate the transport. In a magnetic field the hybridization is shown to be selectively suppressed due to spin effects.Comment: 4 pages, 4 figure

Impact of tunnel barrier strength on magnetoresistance in carbon nanotubes

We investigate magnetoresistance in spin valves involving CoPd-contacted carbon nanotubes. Both temperature and bias voltage dependence clearly indicate tunneling magnetoresistance as the origin. We show that this effect is significantly affected by the tunnel barrier strength, which appears to be one reason for the variation between devices previously detected in similar structures. Modeling the data by means of the scattering matrix approach, we find a non-trivial dependence of the magnetoresistance on the barrier strength. Furthermore, analysis of the spin precession observed in a nonlocal Hanle measurement yields a spin lifetime of $\tau_s = 1.1\,$ns, a value comparable with those found in silicon- or graphene-based spin valve devices.Comment: 10 pages, 5 figures, 1 tabl

Phänotypische und stoffwechselphysiologische Charakterisierung von ENU- (Ethylnitrosoharnstoff-) induzierten Mausmutanten mit gestörter Körpergewichtsregulation

Bei der ENU-Mutagenese und nachfolgenden phänotypischen Charakterisierung handelt es sich um einen am am Phänotyp orientierten, nicht Hypothesen-basierten Ansatz zur Gen-Funktionsanalyse (forward genetics). In dieser Arbeit erfolgte eine phänotypische und stoffwechselphysiologische Charakterisierung der bislang unbeschriebenen, zwergwüchsigen ENU-induzierten Mauslinien SMA1 und David. SMA1-Mäuse tragen eine (a zu g)-Transition im Exon 5 des GH- (Wachstumshormon, growth hormone) Gens, der auf Proteinebene zu einem D167G Austausch führt. Möglicherweise handelt es sich beim SMA1-GH um ein dominant negatives Protein, dass die Speicherung und/oder Sekretion von GH aus den somatotrophen Zellen der Hypophyse stört und zu verringerten GH- und IGF-1-Spiegeln und damit verbundenem Zwergwuchs führt. Art und Lage der für den David-Phänotyp verantwortlichen Mutation sind dagegen bis heute unbekannt. Der David-Phänotyp wurde aufgrund seines geringeren Körperfettgehalts (%) als mögliches Tiermodell für Anorexie (Magersucht) erachtet. Ziel der Arbeit war die Etablierung und Durchführung eines phänotypischen und stoffwechselphysiologischen Charakterisierungsprogramms für ENU-induzierte Mausmutanten mit gestörter Körpergewichtsregulation am Beispiel der SMA1-Maus. Sind SMA1-Mäuse metabolisch „nur” kleiner? Im Rahmen der Arbeit wurden ausgewählte Stellgrößen des Energiehaushalts von Säugetieren untersucht (Wärmeproduktion, Körpertemperatur und Assimilation). Es konnte gezeigt werden, dass SMA1 Mäuse fettleibig werden. Diese Störung in der Körpergewichtsregulation wird vermutlich durch Hyperghrelinämie, eine erniedrigte Körpertemperatur, Hyperphagie und einen verringerten täglichen Gesamtenergieverbrauch begünstigt. Teile des für die SMA1-Mauslinie etablierten Phänotypisierungsprogramms wurden nachfolgend für die Untersuchung von David-Mäusen eingesetzt: Die Ergebnisse der metabolischen Analysen von David zeigen, dass diese Mutante kein geeignetes Tiermodell für Anorexie darstellt. Vielmehr stützen die Ergebnisse eine proportional mit der Körpermasse verringerte Änderung im Körperfettgehalt und im Energiehaushalt

Vom Hörsaal bis ins Klassenzimmer – Längsschnittliche fachliche Vernetzungen in der Lehramtsausbildung

Maßnahmen im Rahmen der Qualitätsoffensive Lehrerbildung der Universität Marbur

Rolle der Src-Kinasen in den Signaltransduktionswegen von Interleukin-6 und Erythropoetin

Wir zeigten in dieser Arbeit, dass Mitglieder der Src-Kinasen Familie durch IL-6 und Epo aktiviert werden und mit deren Rezeptoren, vor allem dem EpoR, assoziieren. Darüber hinaus scheint die Src-Kinase Lyn eine Rolle in der erythrozytären Differenzierung zu spielen

Molecular monitoring of minimal residual disease in two patients with MLL-rearranged acute myeloid leukemia and haploidentical transplantation after relapse

This report describes the clinical courses of two acute myeloid leukemia patients. Both had MLL translocations, the first a t(10;11)(p11.2;q23) with MLL-AF10 and the second a t(11;19)(q23;p13.1) with MLL-ELL fusion. They achieved a clinical remission under conventional chemotherapy but relapsed shortly after end of therapy. Both had a history of invasive mycoses (one had possible pulmonary mycosis, one systemic candidiasis). Because no HLA-identical donor was available, a haploidentical transplantation was performed in both cases. Using a specially designed PCR method for the assessment of minimal residual disease (MRD), based on the quantitative detection of the individual chromosomal breakpoint in the MLL gene, all patients achieved complete and persistent molecular remission after transplantation. The immune reconstitution after transplantation is described in terms of total CD3+/CD4+, CD3+/CD8+, CD19+, and CD16+/CD56+ cell numbers over time. The KIR and HLA genotypes of donors and recipients are reported and the possibility of a KIR-mediated alloreactivity is discussed. This report illustrates that haploidentical transplantation may offer a chance of cure without chronic graft-versus-host disease in situations where no suitable HLA-identical donor is available even in a high-risk setting and shows the value of MRD monitoring in the pre- and posttransplant setting

Nanoscale X-ray investigation of magnetic metallofullerene peapods

Endohedral lanthanide ions packed inside carbon nanotubes (CNTs) in a one-dimensional assembly have been studied with a combination of high resolution transmission electron microscopy (HRTEM), scanning transmission X-ray microscopy (STXM), and X-ray magnetic circular dichroism (XMCD). By correlating HRTEM and STXM images we show that structures down to 30 nm are resolved with chemical contrast and record X-ray absorption spectra from endohedral lanthanide ions embedded in individual nanoscale CNT bundles. XMCD measurements of an Er$_3$N@C$_{80}$ bulk sample and a macroscopic assembly of filled CNTs indicates that the magnetic properties of the endohedral Er3+ ions are unchanged when encapsulated in CNTs. This study demonstrates the feasibility of local magnetic X-ray characterization of low concentrations of lanthanide ions embedded in molecular nanostructures

On the functional relationship between biodiversity and economic value

Biodiversity’s contribution to human welfare has become a key argument for maintaining and enhancing biodiversity in managed ecosystems. The functional relationship between biodiversity (b) and economic value (V) is, however, insufficiently understood, despite the premise of a positive-concave bV relationship that dominates scientific and political arenas. Here, we review how individual links between biodiversity, ecosystem functions (F), and services affect resulting bV relationships. Our findings show that bV relationships are more variable, also taking negative-concave/convex or strictly concave and convex forms. This functional form is driven not only by the underlying bF relationship but also by the number and type of ecosystem services and their potential trade-offs considered, the effects of inputs, and the type of utility function used to represent human preferences. Explicitly accounting for these aspects will enhance the substance and coverage of future valuation studies and allow more nuanced conclusions, particularly for managed ecosystems