All-electrical measurement of spin injection in a magnetic pp-nn junction diode

Magnetic $p$-$n$ junction diodes are fabricated to investigate spin-polarized electron transport. The injection of spin-polarized electrons in a semiconductor is achieved by driving a current from a ferromagnetic injector (Fe), into a bulk semiconductor ($n$-GaAs) via schottky contact. For detection, a diluted magnetic semiconductor ($p$-GaMnAs) layer is used. Clear magnetoresistance was observed only when a high forward bias was applied across the $p$-$n$ junction.Comment: 4 pages, 4 figure

A Quantitative Model for Using Open Innovation in Mobile Service Development

The potential of mobile service innovations to create valuable economic impact makes their development desirable for companies. To develop and launch successful mobile services, the integration of customers in the idea generation process bears high potential. However, such Open Innovation activities usually demand for investments, whereas the precise relation between the money invested and the generated economic effect is still indistinct. The objective of this paper is to replace the black box between investments in Open Innovation and the thereby generated profits through formal-deductive analysis. For this purpose, we analyze the effect chain between Open Innovation and economic profit by adapting the model of Kano and putting special emphasis on the specifics of mobile services. Building on that, we develop a quantitative formal model to determine the optimal investment amount in Open Innovation activities for mobile services. The model’s utility is illustrated with an example based on real-world data

Quantum Chaos and Quantum Randomness - Paradigms of Entropy Production on the Smallest Scales

Quantum chaos is presented as a paradigm of information processing by dynamical systems at the bottom of the range of phase-space scales. Starting with a brief review of classical chaos as entropy flow from micro- to macro-scales, I argue that quantum chaos came as an indispensable rectification, removing inconsistencies related to entropy in classical chaos: Bottom-up information currents require an inexhaustible entropy production and a diverging information density in phase space, reminiscent of Gibbs' paradox in Statistical Mechanics. It is shown how a mere discretization of the state space of classical models already entails phenomena similar to hallmarks of quantum chaos, and how the unitary time evolution in a closed system directly implies the ''quantum death'' of classical chaos. As complementary evidence, I discuss quantum chaos under continuous measurement. Here, the two-way exchange of information with a macroscopic apparatus opens an inexhaustible source of entropy and lifts the limitations implied by unitary quantum dynamics in closed systems. The infiltration of fresh entropy restores permanent chaotic dynamics in observed quantum systems. Could other instances of stochasticity in quantum mechanics be interpreted in a similar guise? Where observed quantum systems generate randomness, that is, produce entropy without discernible source, could it have infiltrated from the macroscopic meter? This speculation is worked out for the case of spin measurement.Comment: 41 pages, 17 figure

The Ratio of ADP- to TRAP-Induced Platelet Aggregation Quantifies P2Y(12)-Dependent Platelet Inhibition Independently of the Platelet Count

Objective This study aimed to assess the association of clinical factors with P2Y(12)-dependent platelet inhibition as monitored by the ratio of ADP-to TRAP-induced platelet aggregation and conventional ADP-induced aggregation, respectively. Background Controversial findings to identify and overcome high platelet reactivity (HPR) after coronary stent-implantation and to improve clinical outcome by tailored anti-platelet therapy exist. Monitoring anti-platelet therapy ex vivo underlies several confounding parameters causing that ex vivo platelet aggregation might not reflect in vivo platelet inhibition. Methods In a single centre observational study, multiple electrode aggregometry was performed in whole blood of patients after recent coronary stent-implantation. Relative ADP-induced aggregation (r-ADP-agg) was defined as the ratio of ADP-to TRAP-induced aggregation reflecting the individual degree of P2Y(12)-mediated platelet reactivity. Results Platelet aggregation was assessed in 359 patients. Means (+/- SD) of TRAP-, ADP-induced aggregation and r-ADP-agg were 794 +/- 239 AU* min, 297 +/- 153 AU* min and 37 +/- 14%, respectively. While ADP-and TRAP-induced platelet aggregation correlated significantly with platelet count (ADP: r = 0.302;p< 0.001;TRAP: r = 0.509 p< 0.001), r-ADP-agg values did not (r = -0.003;p = 0.960). These findings were unaltered in multivariate analyses adjusting for a range of factors potentially influencing platelet aggregation. The presence of an acute coronary syndrome and body weight were found to correlate with both ADP-induced platelet aggregation and r-ADP-agg. Conclusion The ratio of ADP-to TRAP-induced platelet aggregation quantifies P2Y(12)-dependent platelet inhibition independently of the platelet count in contrast to conventional ADP-induced aggregation. Furthermore, r-ADP-agg was associated with the presence of an acute coronary syndrome and body weight as well as ADP-induced aggregation. Thus, the r-ADP-agg is a more valid reflecting platelet aggregation and potentially prognosis after coronary stent-implantation in P2Y(12)-mediated HPR than conventional ADP-induced platelet aggregation

Bioorthogonal site-selective conjugation of fluorescent dyes to antibodies: method and potential applications

Antibodies are immensely useful tools for biochemical research and have found application in numerous protein detection and purification methods. Moreover, monoclonal antibodies are increasingly utilised as therapeutics or, conjugated to active pharmaceutical ingredients, in targeted chemotherapy. Several reagents and protocols are reported to synthesise fluorescent antibodies for protein target detection and immunofluorescence applications. However, most of these protocols lead to non-selective conjugation, over-labelling or in the worst case antigen binding site modification. Here, we have used the antibody disulphide cleavage and re-bridging strategy to introduce bright fluorescent dyes without loss of the antibody function. The resulting fluorescent IgG1 type antibodies were shown to be effective imaging tools in western blot and direct immunofluorescence experiments

Real-time motion and retrospective coil sensitivity correction for CEST using volumetric navigators (vNavs) at 7T

Purpose To explore the impact of temporal motion-induced coil sensitivity changes on CEST-MRI at 7T and its correction using interleaved volumetric EPI navigators, which are applied for real-time motion correction. Methods Five healthy volunteers were scanned via CEST. A 4-fold correction pipeline allowed the mitigation of (1) motion, (2) motion-induced coil sensitivity variations, Delta B1-, (3) motion-induced static magnetic field inhomogeneities, Delta B-0, and (4) spatially varying transmit RF field fluctuations, Delta B1+. Four CEST measurements were performed per session. For the first 2, motion correction was turned OFF and then ON in absence of voluntary motion, whereas in the other 2 controlled head rotations were performed. During post-processing Delta B1- was removed additionally for the motion-corrected cases, resulting in a total of 6 scenarios to be compared. In all cases, retrospective increment B-0 and -Delta B1+ corrections were performed to compute artifact-free magnetization transfer ratio maps with asymmetric analysis (MTRasym). Results Dynamic Delta B1- correction successfully mitigated signal deviations caused by head motion. In 2 frontal lobe regions of volunteer 4, induced relative signal errors of 10.9% and 3.9% were reduced to 1.1% and 1.0% after correction. In the right frontal lobe, the motion-corrected MTRasym contrast deviated 0.92%, 1.21%, and 2.97% relative to the static case for Delta omega = 1, 2, 3 +/- 0.25 ppm. The additional application of Delta B1- correction reduced these deviations to 0.10%, 0.14%, and 0.42%. The fully corrected MTRasym values were highly consistent between measurements with and without intended head rotations. Conclusion Temporal Delta B1- cause significant CEST quantification bias. The presented correction pipeline including the proposed retrospective Delta B1- correction significantly reduced motion-related artifacts on CEST-MRI.Peer reviewe