A Mean Field Model for the Quadrupolar Phases of UPd3_3

UPd$_3$ is known to exhibit four antiferroquadrupolar ordered phases at low temperatures. We report measurements of the magnetisation and magnetostriction of single crystal UPd$_3$, along the principal symmetry directions, in fields up to 33 T. These results have been combined with recent inelastic neutron and x-ray resonant scattering measurements to construct a mean field model of UPd$_3$ including up to fourth nearest neighbour interactions. In particular we find that anisotropic quadrupolar interactions must be included in order to explain the low temperature structures derived from the scattering data.Comment: 9 pages, 6 figures, 3 table

Ontology Based Integration of Distributed and Heterogeneous Data Sources in ACGT.

In this work, we describe the set of tools comprising the Data Access Infrastructure within Advancing Clinic-genomic Trials on Cancer (ACGT), a R&D Project funded in part by the European. This infrastructure aims at improving Post-genomic clinical trials by providing seamless access to integrated clinical, genetic, and image databases. A data access layer, based on OGSA-DAI, has been developed in order to cope with syntactic heterogeneities in databases. The semantic problems present in data sources with different nature are tackled by two core tools, namely the Semantic Mediator and the Master Ontology on Cancer. The ontology is used as a common framework for semantics, modeling the domain and acting as giving support to homogenization. SPARQL has been selected as query language for the Data Access Services and the Mediator. Two experiments have been carried out in order to test the suitability of the selected approach, integrating clinical and DICOM image databases

Comment on 'Nonreciprocal light propagation in a silicon photonic circuit'

We show that the structure demonstrated by Feng et al. (Reports, 5 August 2011, p. 729) cannot enable optical isolation because it possesses a symmetric scattering matrix. Moreover, one cannot construct an optical isolator by incorporating this structure into any system as long as the system is linear and time-independent and is described by materials with a scalar dielectric function

Rich Magnetic Phase Diagram of Putative Helimagnet Sr3_3Fe2_2O7_7

The cubic perovskite SrFeO$_3$ was recently reported to host hedgehog- and skyrmion-lattice phases in a highly symmetric crystal structure which does not support the Dzyaloshinskii-Moriya interactions commonly invoked to explain such magnetic order. Hints of a complex magnetic phase diagram have also recently been found in powder samples of the single-layer Ruddlesden-Popper analog Sr$_2$FeO$_4$, so a reinvestigation of the bilayer material Sr$_3$Fe$_2$O$_7$, believed to be a simple helimagnet, is called for. Our magnetization and dilatometry studies reveal a rich magnetic phase diagram with at least 6 distinct magnetically ordered phases and strong similarities to that of SrFeO$_3$. In particular, at least one phase is apparently multiple-$\mathbf{q}$, and the $\mathbf{q}$s are not observed to vary among the phases. Since Sr$_3$Fe$_2$O$_7$ has only two possible orientations for its propagation vector, some of the phases are likely exotic multiple-$\mathbf{q}$ order, and it is possible to fully detwin all phases and more readily access their exotic physics.Comment: 14 pages, 13 figure

Magnetic Phase Diagram of Rouaite, Cu2_2(OH)3_3NO3_3

Spinon-magnon mixing was recently reported in botallackite Cu$_2$(OH)$_3$Br with a uniaxially compressed triangular lattice of Cu$^{2+}$ quantum spins [Zhang et al., Phys. Rev. Lett. 125, 037204 (2020)]. Its nitrate counterpart rouaite, Cu$_2$(OH)$_3$NO$_3$, has a highly analogous structure and might be expected to exhibit similar physics. To lay a foundation for research on this material, we clarify rouaite\u27s magnetic phase diagram and identify both low-field phases. The low-temperature magnetic state consists of alternating ferro- and antiferromagnetic chains, as in botallackite, but with additional canting, leading to net moments on all chains which rotate from one chain to another to form a 90$^\circ$ cycloidal pattern. The higher-temperature phase is a helical modulation of this order, wherein the spins rotate from one Cu plane to the next. This extends to zero temperature for fields perpendicular to the chains, leading to a set of low-temperature field-induced phase transitions. Rouaite may offer another platform for spinon-magnon mixing, while our results suggest a delicate balance of interactions and high tunability of the magnetism.21 pages, 21 figures; CIF files describing the refinements provided as ancillary file

Protein-coding variants implicate novel genes related to lipid homeostasis contributing to body-fat distribution

Body-fat distribution is a risk factor for adverse cardiovascular health consequences. We analyzed the association of body-fat distribution, assessed by waist-to-hip ratio adjusted for body mass index, with 228,985 predicted coding and splice site variants available on exome arrays in up to 344,369 individuals from five major ancestries (discovery) and 132,177 European-ancestry individuals (validation). We identified 15 common (minor allele frequency, MAF ≥5%) and nine low-frequency or rare (MAF &lt;5%) coding novel variants. Pathway/gene set enrichment analyses identified lipid particle, adiponectin, abnormal white adipose tissue physiology and bone development and morphology as important contributors to fat distribution, while cross-trait associations highlight cardiometabolic traits. In functional follow-up analyses, specifically in Drosophila RNAi-knockdowns, we observed a significant increase in the total body triglyceride levels for two genes (DNAH10 and PLXND1). We implicate novel genes in fat distribution, stressing the importance of interrogating low-frequency and protein-coding variants.</p

Magnetostriction in rare-earth bases antiferromagnets

Magnetostriction in rare-earth based antiferromagnets M. Doerr A1, M. Rotter A2, A. Lindbaum A3 A1 Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden, Germany A2 Institut für Physikalische Chemie, Universität Wien, Währingerstaße 42, A-1090 Wien, Austria A3 Institut für Festkörperphysik, Technische Universität Wien, Wiedner Hauptstraße 8-10, A-1040 Wien, Austria Abstract: Magnetostriction in systems with rare-earth elements is a very general topic of interest because it characterizes the electronic magnetism of compounds as well as the interaction of the magnetic and the lattice system. The magnetostrictive behaviour of classical ferromagnets is widely investigated. The interpretation of the data is based on domain dynamics, crystal field effects and other magnetoelastic mechanisms, which are extremely difficult to separate. Therefore, in the last few years there has been great activity in the area of magnetostriction of antiferromagnets. In contrast to ferromagnets, in antiferromagnets a large variety of magnetic structures can be stabilized at different temperatures and magnetic fields. This fundamental property of antiferromagnets allows one to separate and distinguish the different mechanisms of magnetostriction. New classes of magnetic compounds with antiferromagnetic order, for example the borocarbides and some special manganites, have also focused research efforts on the magnetostrictive behaviour in order to gain a more complex picture of these materials. In particular, changes of symmetry caused by lattice distortions attracted great interest. Moreover, some antiferromagnetic compounds with giant magnetostrictive effects of more than 1% have been found and the number of publications in this area is growing. The aim of the present review is to summarize experimental data as well as theoretical models concerning spontaneous and forced magnetostriction in antiferromagnetic systems, where the magnetic properties are dominated by the rare-earth magnetism. Above this, the available data, which were acquired with different motivations and therefore are of heterogeneous character, are systematized. After a summary of experimental methods the standard model of rare-earth based magnetostriction is reviewed. Then experimentally determined expansion and magnetostriction data of the pure rare-earth metals are discussed followed by selected rare-earth compounds and giant magnetostriction materials. The potential of a theoretical model which takes into account the crystal field effects as well as the (anisotropic) exchange striction is demonstrated in the interpretation of some of the experimental data