Chiral Phonons with Giant Magnetic Moments in a Topological Crystalline Insulator

We have studied the magnetic response of transverse optical phonons in Pb$_{1-x}$Sn$_{x}$Te films. Polarization-dependent terahertz magnetospectroscopy measurements revealed Zeeman splittings and diamagnetic shifts, demonstrating that these phonon modes become chiral in magnetic fields. Films in the topological crystalline insulator phase ($x > 0.32$) exhibited magnetic moment values that are larger than those for topologically trivial films ($x < 0.32$) by two orders of magnitude. Furthermore, the sign of the effective $g$-factor was opposite in the two phases, which can be explained by our theoretical model. These results strongly hint at the existence of interplay between the magnetic properties of chiral phonons and the topology of electronic band structure.Comment: 6 pages, 3 figures, see Supplemental Material in the Ancillary director

Magnetic Control of Soft Chiral Phonons in PbTe

PbTe crystals have a soft transverse optical phonon mode in the terahertz frequency range, which is known to efficiently decay into heat-carrying acoustic phonons, resulting in anomalously low ther- mal conductivity. Here, we studied this phonon via polarization-dependent terahertz spectroscopy. We observed softening of this mode with decreasing temperature, indicative of incipient ferroelectric- ity, which we explain through a model including strong anharmonicity with a quartic displacement term. In magnetic fields up to 25 T, the phonon mode splits into two modes with opposite hand- edness, exhibiting circular dichroism. Their frequencies display Zeeman splitting together with an overall diamagnetic shift with increasing magnetic field. Using a group-theoretical approach, we demonstrate that these observations are the result of magnetic field-induced morphic changes in the crystal symmetries through the Lorentz force exerted on the lattice ions. Our study thus reveals a novel process of controlling phonon properties in a soft ionic lattice by a strong magnetic field.This research was primarily sup- ported by the National Science Foundation through the Center for Dynamics and Control of Materials: an NSF MRSEC under Cooperative Agreement No. DMR- 1720595. F.G.G.H. acknowledges financial support from the Brasil@Rice Collaborative Grant, the So Paulo Re- search Foundation (FAPESP) Grants No. 2015/16191-5 and No. 2018/06142-5, and Grant No. 307737/2020-9 of the National Council for Scientific and Technological Development (CNPq). M. R-V. was supported by LANL LDRD Program and by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sci- ences and Engineering Division, Condensed Matter The- ory Program. G. A. F. acknowledges additional support from NSF DMR-1949701 and NSF DMR-2114825. J. T. and I. K. acknowledge the support from the Japan Soci- ety for the Promotion of Science (JSPS) (KAKENHI No. 20H05662).Center for Dynamics and Control of Material

Automotive UML. A (Meta) Model-Based Approach for Systems Development

von der Beeck M, Braun P, Rappl M, Schröder C. Automotive UML. A (Meta) Model-Based Approach for Systems Development. In: Lavagno L, Martin G, Selic B, eds. UML for Real: Design of Embedded Real-Time Systems. Boston, MA: Springer US; 2003: 271-299.In this chapter a recent approach is described which utilizes the Unified Modeling Language (UML) within the automotive specific systems development. In particular it presents the Automotive Modeling Language (AML), a modeling language tailored to the development needs of automotive embedded systems. A focus is set on the definition of a metamodel for the AML, as well as on a system of abstraction levels, and on a tight integration between requirements engineering and model-based descriptions. Furthermore the concrete AML representation is given by a concrete UML subset, which is called ``Automotive UML''. The application of the introduced language concepts is illustrated by means of a realistic case study from the automotive domain

Modeling Embedded Software: State of the Art and Beyond

State-of-the-art software development increasingly relies on describing the system (or software) graphically, abstracting from an actual implementation platform, and supporting to generate an executable system out of the model. Similarly, in electrical engineering often graphically represented models are used to describe the controlled system including its low-level control behavior. Since developing embedded software requires using abstract, functional models of the software as well as incorporating aspects from the implemented algorithmic behavior, a suitable model-based development process must integrate models from both fields. By comparing the results from modeling an automotive embedded controller software module with eight different state-of-the art CASE tools, we show what kind of abstractions, views, and models have proven useful in that domain. Furthermore, we show what analytical and generative development steps are currently supported by CASE tools. Based on those experiences and results from other research on efficiency and effectiveness of software engineering techniques and CASE support, we derive the properties of a model-based development process and illustrate it by example support functionalities

Characterization and Evolution of Cell Division and Cell Wall Synthesis Genes in the Bacterial Phyla Verrucomicrobia, Lentisphaerae, Chlamydiae, and Planctomycetes and Phylogenetic Comparison with rRNA Genes▿ †

In the past, studies on the relationships of the bacterial phyla Planctomycetes, Chlamydiae, Lentisphaerae, and Verrucomicrobia using different phylogenetic markers have been controversial. Investigations based on 16S rRNA sequence analyses suggested a relationship of the four phyla, showing the branching order Planctomycetes, Chlamydiae, Verrucomicrobia/Lentisphaerae. Phylogenetic analyses of 23S rRNA genes in this study also support a monophyletic grouping and their branching order—this grouping is significant for understanding cell division, since the major bacterial cell division protein FtsZ is absent from members of two of the phyla Chlamydiae and Planctomycetes. In Verrucomicrobia, knowledge about cell division is mainly restricted to the recent report of ftsZ in the closely related genera Prosthecobacter and Verrucomicrobium. In this study, genes of the conserved division and cell wall (dcw) cluster (ddl, ftsQ, ftsA, and ftsZ) were characterized in all verrucomicrobial subdivisions (1 to 4) with cultivable representatives (1 to 4). Sequence analyses and transcriptional analyses in Verrucomicrobia and genome data analyses in Lentisphaerae suggested that cell division is based on FtsZ in all verrucomicrobial subdivisions and possibly also in the sister phylum Lentisphaerae. Comprehensive sequence analyses of available genome data for representatives of Verrucomicrobia, Lentisphaerae, Chlamydiae, and Planctomycetes strongly indicate that their last common ancestor possessed a conserved, ancestral type of dcw gene cluster and an FtsZ-based cell division mechanism. This implies that Planctomycetes and Chlamydiae may have shifted independently to a non-FtsZ-based cell division mechanism after their separate branchings from their last common ancestor with Verrucomicrobia

Endogenous Il10 Alleviates the Systemic Antiviral Cellular Immune Response and T Cell-Mediated Immunopathology in Select Organs of Acutely LCMV-Infected Mice

The immunoregulatory cytokine IL-10 suppresses T-cell immunity. The complementary question, whether IL-10 is also involved in Limiting the collateral damage of vigorous T cell responses, has not been addressed in detail. Here, we report that the particularly strong virus-specific immune response during acute primary infection with the Lymphocytic choriomeningitis virus (LCMV) in mice is significantly further increased in Il10 deficient mice, particularly regarding frequencies and cytotoxic activity of CD8(+) T cells. This increase results in exacerbating immunopathology in select organs, ranging from transient local swelling to an increased risk for mortality. Remarkably, LCMV-induced, T cell mediated hepatitis is not affected by endogenous Il10. The alleviating effect of Il10 on LCMV-induced immunopathology was found to be operative in delayed-type hypersensitivity footpad-swelling reaction and in debilitating meningitis in mice of both the C57BL/6 and BALB/c strains. These strains are prototypic counterpoles for genetically imprinted type 1-biased versus type 2-biased T cell mediated immune responses against various infectious pathogens. However, during acute LCMV infection, neither systemic cytokine patterns nor the impact of Il10 on LCMV-induced immunopathology differed conspicuously between these two strains of mice. This study documents a physiological role of Il10 in the regulation of a balanced T-cell response limiting immunopathological damage