250 research outputs found
Investigation on MnGa/MgO interface for magnetic tunneling junctions
The MnGa Heusler compound and related alloys are the most promising
materials for the realization of spin-transfer-torque switching in magneto
tunneling junctions. Improved performance can be achieved by high quality
interfaces in these multilayered structured devices. In this context, the
interface between MnGa and MgO is of particular interest because of
its spin polarization properties in tunneling junctions. We performed a
chemical characterization of the MgO/MnGa junction by hard x-ray
photoelectron spectroscopy (HAXPES). The experiment indicated the formation of
Ga-O bonds at the interface and evidenced changes in the local environment of
Mn atoms in the proximity of the MgO film. In addition, we show that the
insertion of a metallic Mg-layer interfacing the MgO and Mn--Ga film strongly
suppresses the oxidation of gallium
Improving thermoelectric performance of TiNiSn by mixing MnNiSb in the half-Heusler structure
The thermoelectric properties of n type semiconductor, TiNiSn is optimized by
partial substitution with metallic, MnNiSb in the half Heusler structure.
Herein, we study the transport properties and intrinsic phase separation in the
system. The Ti1-xMnxNiSn1-xSbx alloys were prepared by arc-melting and were
annealed at temperatures obtained from differential thermal analysis and
differential scanning calorimetry results. The phases were characterized using
powder X-ray diffraction patterns, energy dispersive X-ray spectroscopy, and
differential scanning calorimetry. After annealing the majority phase was
TiNiSn with some Ni rich sites and the minority phases was majorly Ti6Sn5, Sn,
and MnSn2. Ni rich sites were caused by Frenkel defects, this led to a
metal-like behavior of the semiconducting specimens at low temperature. For x
up to 0.05 the samples showed an activated conduction, whereas for x>0.05 they
showed metallic character. The figure of merit for x=0.05 was increased by 61%
(ZT=0.45) in comparison to the pure TiNiSn.Comment: 7 pages and 5 figures. Submitted to Physical Chemistry Chemical
Physics - RSC Publishing on 6th of October, 201
Multi-objective Robust Strategy Synthesis for Interval Markov Decision Processes
Interval Markov decision processes (IMDPs) generalise classical MDPs by
having interval-valued transition probabilities. They provide a powerful
modelling tool for probabilistic systems with an additional variation or
uncertainty that prevents the knowledge of the exact transition probabilities.
In this paper, we consider the problem of multi-objective robust strategy
synthesis for interval MDPs, where the aim is to find a robust strategy that
guarantees the satisfaction of multiple properties at the same time in face of
the transition probability uncertainty. We first show that this problem is
PSPACE-hard. Then, we provide a value iteration-based decision algorithm to
approximate the Pareto set of achievable points. We finally demonstrate the
practical effectiveness of our proposed approaches by applying them on several
case studies using a prototypical tool.Comment: This article is a full version of a paper accepted to the Conference
on Quantitative Evaluation of SysTems (QEST) 201
Large linear non-saturating magnetoresistance and high mobility in ferromagnetic MnBi
A large non-saturating magnetoresistance has been observed in several nonmagnetic topological Weyl semi-metals with high mobility of charge carriers at the Fermi energy. However, ferromagnetic systems rarely display a large magnetoresistance because of localized electrons in heavy d bands with a low Fermi velocity. Here, we report a large linear non-saturating magnetoresistance and high mobility in ferromagnetic MnBi. MnBi, unlike conventional ferromagnets, exhibits a large linear non-saturating magnetoresistance of 5000% under a pulsed field of 70 T. The electrons and holesâ mobilities are both 5000 cm2Vâ1sâ1 at 2 K, which are one of the highest for ferromagnetic materials. These phenomena are due to the spin-polarised Bi 6p bandâs sharp dispersion with a small effective mass. Our study provides an approach to achieve high mobility in ferromagnetic systems with a high Curie temperature, which is advantageous for topological spintronics. © 2021, The Author(s)
Gewalt gegen Rettungsdienstpersonal
Aktuell werden Angriffe gegen Rettungsdienstpersonal medial und politisch vermehrt diskutiert, was u. a. politische Initiativen und GesetzesĂ€nderungen zur Folge hat. Es wird konstatiert, dass die wissenschaftliche Studienlage in Deutschland insbesondere in Hinsicht auf die PrĂ€valenzen solcher VorfĂ€lle lĂŒckenhaft ist. Zwischen Mai bis August 2021 wurden im Rahmen einer Langzeitbefragung das Rettungsdienstpersonal mit Hilfe eines Onlinefragebogens befragt und qualitative Interviews mit Experten und Expertinnen bzw. Betroffenen gefĂŒhrt. Neben den HĂ€ufigkeiten von Gewaltdelikten wurden Eskalationsfaktoren sowie Folgen der VorfĂ€lle fĂŒr die betroffenen EinsatzkrĂ€fte erhoben. Es zeigt sich, dass Angriffe, insbesondere verbaler Art, zum Arbeitsalltag von Rettungsdienstpersonal gehören. Im Durchschnitt wurden wöchentlich 29 % der Befragten beleidigt, belĂ€stigt oder verbal bedroht. Pro Woche waren 8 % der Befragten körperlichen Angriffen ausgesetzt. Die Betroffenen Ă€uĂern den Wunsch nach Nachbetreuung und eine Anpassung der Ausbildungslage. Empfohlen werden Schulungen, die fĂŒr Gefahren sensibilisieren, DeeskalationsansĂ€tze in den Blick nehmen und Eigensicherung thematisieren
Acute leukaemoid reaction following cardiac surgery
Chronic myelomonocytic leukaemia is an atypical myeloproliferative disorder with a natural history of progression to acute myeloid leukaemia, a complex and poorly understood response by the bone marrow to stress. Cardiac surgery activates many inflammatory cascades and may precipitate a systemic inflammatory response syndrome. We present a case of undiagnosed chronic myelomonocytic leukaemia who developed rapidly fatal multi-organ dysfunction following cardiac surgery due to an acute leukaemoid reaction
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