The Biaxial Strain Dependence of Magnetic Order in Spin Frustrated Mn3NiN Thin Films

Multicomponent magnetic phase diagrams are a key property of functional materials for a variety of uses, such as manipulation of magnetization for energy efficient memory, data storage, and cooling applications. Strong spin‐lattice coupling extends this functionality further by allowing electric‐field‐control of magnetization via strain coupling with a piezoelectric. Here this work explores the magnetic phase diagram of piezomagnetic Mn₃NiN thin films, with a frustrated noncollinear antiferromagnetic (AFM) structure, as a function of the growth induced biaxial strain. Under compressive strain, the films support a canted AFM state with large coercivity of the transverse anomalous Hall resistivity, ρ_xy, at low temperature, that transforms at a well‐defined Néel transition temperature (T_N) into a soft ferrimagnetic‐like (FIM) state at high temperatures. In stark contrast, under tensile strain, the low temperature canted AFM phase transitions to a state where ρ_xy is an order of magnitude smaller and therefore consistent with a low magnetization phase. Neutron scattering confirms that the high temperature FIM‐like phase of compressively strained films is magnetically ordered and the transition at T_N is first‐order. The results open the field toward future exploration of electric‐field‐driven piezospintronic and thin film caloric cooling applications in both Mn₃NiN itself and the broader Mn₃AN family.     

Shedding Light on Metal‐Based Nanoparticles in Zebrafish by Computed Tomography with Micrometer Resolution

Metal‐based nanoparticles are clinically used for diagnostic and therapeutic applications. After parenteral administration, they will distribute throughout different organs. Quantification of their distribution within tissues in the 3D space, however, remains a challenge owing to the small particle diameter. In this study, synchrotron radiation‐based hard X‐ray tomography (SRμCT) in absorption and phase contrast modes is evaluated for the localization of superparamagnetic iron oxide nanoparticles (SPIONs) in soft tissues based on their electron density and X‐ray attenuation. Biodistribution of SPIONs is studied using zebrafish embryos as a vertebrate screening model. This label‐free approach gives rise to an isotropic, 3D, direct space visualization of the entire 2.5 mm‐long animal with a spatial resolution of around 2 µm. High resolution image stacks are available on a dedicated internet page ( http://zebrafish.pharma-te.ch ). X‐ray tomography is combined with physico‐chemical characterization and cellular uptake studies to confirm the safety and effectiveness of protective SPION coatings. It is demonstrated that SRμCT provides unprecedented insights into the zebrafish embryo anatomy and tissue distribution of label‐free metal oxide nanoparticles.     

Chemical,Structural, and Electronic Aspects of Formation and Degradation Behavior on Different Length Scales of Ni‐Rich NCM and Li‐Rich HE‐NCM Cathode Materials in Li‐Ion Batteries

In order to satisfy the energy demands of the electromobility market, both Ni‐rich and Li‐rich layered oxides of NCM type are receiving much attention as high‐energy‐density cathode materials for application in Li‐ion batteries. However, due to different stability issues, their longevity is limited. During formation and continuous cycling, especially the electronic and crystal structure suffers from various changes, eventually leading to fatigue and mechanical degradation. In recent years, comprehensive battery research has been conducted at Karlsruhe Institute of Technology, mainly aiming at better understanding the primary degradation processes occurring in these layered transition metal oxides. The characteristic process of formation and mechanisms of fatigue are fundamentally characterized and the effect of chemical composition on cell chemistry, electrochemistry, and cycling stability is addressed on different length scales by use of state‐of‐the‐art analytical techniques, ranging from “standard” characterization tools to combinations of advanced in situ and operando methods. Here, the results are presented and discussed within a broader scientific context.     

Human perception of a conversational virtual human: an empirical study on the effect of emotion and culture

Virtual reality applications with virtual humans, such as virtual reality exposure therapy, health coaches and negotiation simulators, are developed for different contexts and usually for users from different countries. The emphasis on a virtual human’s emotional expression depends on the application; some virtual reality applications need an emotional expression of the virtual human during the speaking phase, some during the listening phase and some during both speaking and listening phases. Although studies have investigated how humans perceive a virtual human’s emotion during each phase separately, few studies carried out a parallel comparison between the two phases. This study aims to fill this gap, and on top of that, includes an investigation of the cultural interpretation of the virtual human’s emotion, especially with respect to the emotion’s valence. The experiment was conducted with both Chinese and non-Chinese participants. These participants were asked to rate the valence of seven different emotional expressions (ranging from negative to neutral to positive during speaking and listening) of a Chinese virtual lady. The results showed that there was a high correlation in valence rating between both groups of participants, which indicated that the valence of the emotional expressions was as easily recognized by people from a different cultural background as the virtual human. In addition, participants tended to perceive the virtual human’s expressed valence as more intense in the speaking phase than in the listening phase. The additional vocal emotional expression in the speaking phase is put forward as a likely cause for this phenomenon.     

A planning tool for two-phase case-control studies

We present a software tool for planning two-phase case-control studies assuming categorical covariates. Two-phase designs, in which validation or complete information data are sampled stratified both on a dichotomous outcome and a covariate from a first-phase study with incomplete data, result in efficient estimates compared to standard designs. Efficiency and power depend on sample size, sampling fractions within each stratum x outcome cell, distributional assumptions and the regression model. Our software, called Two-Phase Planning Tool (or 2P Planning Tool), offers a graphical user interface (GUI) to organize and input the relevant anticipated entities and calculates a normed, expected two-phase case-control study. The 2P Planning Tool is especially helpful in selecting a stratification. The data are output into an Excel-sheet, which in turn can be read into a standard statistics package to perform "experimental" power calculations. Its use is illustrated by an example from epidemiology. Software for analyzing logistic two-phase studies is also provided.     

Visual servoing for underactuated VTOL UAVs: a linear,homography‐based framework

The paper concerns the control of vertical take‐off and landing (VTOL) underactuated aerial vehicles (UAVs) in hover flight, on the basis of measurements provided by an onboard video camera. The objective is to stabilize the vehicle to the equilibrium pose associated with an image of a planar target, using a minimal sensor suite and poor knowledge of the environment. By using the homography matrix computed from the camera measurements of the target, stabilizing feedback laws are derived on the basis of the visual data and gyrometer measurements only. Explicit stability conditions on the control parameters are provided, showing that a proper tuning of the control parameters ensures a large robustness margin with only planar target and visibility assumptions, although the target size and orientation, the UAV position, linear velocity and orientation are unknown. Additional issues, such as the use of accelerometers to improve the UAV's positioning in the case of unmodeled dynamics (such as wind), are also considered. Copyright © 2013 John Wiley & Sons, Ltd.     

Optimal and efficient filtering algorithms for table constraints

Filtering algorithms for table constraints can be classified in two categories: constraint-based and value-based. In the constraint-based approaches, the propagation queue only contains information on the constraints that must be reconsidered. For the value-based approaches, the propagation queue also contains information on the removed values. This paper proposes five efficient value-based algorithms for table constraints. Two of them (AC5TCOpt-Tr and AC5TCOpt-Sparse) are proved to have an optimal time complexity of O(r·t+r·d) per table constraint. Substantial experimental results are presented. An empirical analysis is conducted on the effect of the arity of the tables. The experiments show that our propagators are the best when the arity of the table is 3 or 4. Indeed, on instances containing only binary constraints, our algorithms are outperformed by classical AC algorithm AC3rm. AC3rm is dedicated to binary constraints. However, all our algorithms outperform existing state-of-the-art constraint based STR2+ and MDD ^c and the optimal value-based STR3 algorithms on those instances. On instances with small arity tables (up to arity 4), all our algorithms are generally faster than STR2+, MDD ^c and than STR3. AC5TCOpt-Sparse is globally the best propagator on those benchmarks. On benchmarks containing large arity tables (arity 5 or more), each of the three existing state-of-the-art algorithms is the winning strategy on one different benchmark.     

Microcontact Printed BaTiO3 and LaNiO3 Thin Films for Capacitors

There is an ongoing need to develop new technologies to enable further down-scaling of layer thicknesses in multilayer ceramic devices, for example, in multilayer capacitors (MLC). Microcontact printing of chemical solutions of both the dielectric and electrode layers was explored as an economical means of preparing patterned thin films for MLC without requiring photolithography. For this purpose, methanol/acetic acid-based BaTiO₃ solutions were spun onto polydimethylsiloxane stamps, printed onto substrates, pyrolyzed, and crystallized. LaNiO₃ was used as a prototype electrode that could also be microcontact printed. The line edge roughness produced this way was on the order of a tenth of a micrometer, which should enable very small margins. The printed layer thickness was also very uniform. Microcontact printed capacitors with a single dielectric layer were fabricated and found to have dielectric constants >800 with loss tangents <2%. Alignment between subsequent layers is readily achieved. Multilayer dielectric/electrode stacks could be fabricated without cracking or delaminations. Consequently, microcontact printing appears to be a viable potential means of preparing MLC with layer thicknesses in the range of ≤0.2 μm.     

Computational Complexity and Anytime Algorithm for Inconsistency Measurement

Measuring inconsistency degrees of inconsistent knowledge bases is an important problem as it provides context information for facilitating inconsistency handling. Many methods have been proposed to solve this problem and a main class of them is based on some kind of paraconsistent semantics. In this paper, we consider the computational aspects of inconsistency degrees of propositional knowledge bases under 4-valued semantics. We ˉrst give a complete analysis of the computational complexity of computing inconsistency degrees. As it turns out that computing the exact inconsistency degree is intractable, we then propose an anytime algorithm that provides tractable approximations of the inconsistency degree from above and below. We show that our algorithm satisˉes some desirable properties and give experimental results of our implementation of the algorithm.