275 research outputs found
Electrical switching of magnetic order in an orbital Chern insulator
Magnetism typically arises from the joint effect of Fermi statistics and
repulsive Coulomb interactions, which favors ground states with non-zero
electron spin. As a result, controlling spin magnetism with electric fields---a
longstanding technological goal in spintronics and multiferroics---can be
achieved only indirectly. Here, we experimentally demonstrate direct electric
field control of magnetic states in an orbital Chern insulator, a magnetic
system in which non-trivial band topology favors long range order of orbital
angular momentum but the spins are thought to remain disordered. We use van der
Waals heterostructures consisting of a graphene monolayer rotationally faulted
with respect to a Bernal-stacked bilayer to realize narrow and topologically
nontrivial valley-projected moir\'e minibands. At fillings of one and three
electrons per moir\'e unit cell within these bands, we observe quantized
anomalous Hall effects with transverse resistance approximately equal to
, which is indicative of spontaneous polarization of the system into a
single-valley-projected band with a Chern number equal to two. At a filling of
three electrons per moir\'e unit cell, we find that the sign of the quantum
anomalous Hall effect can be reversed via field-effect control of the chemical
potential; moreover, this transition is hysteretic, which we use to demonstrate
nonvolatile electric field induced reversal of the magnetic state. A
theoretical analysis indicates that the effect arises from the topological edge
states, which drive a change in sign of the magnetization and thus a reversal
in the favored magnetic state. Voltage control of magnetic states can be used
to electrically pattern nonvolatile magnetic domain structures hosting chiral
edge states, with applications ranging from reconfigurable microwave circuit
elements to ultralow power magnetic memory.Comment: 21 pages, 17 figure
Variable Na<sub>v</sub>1.5 Protein Expression from the Wild-Type Allele Correlates with the Penetrance of Cardiac Conduction Disease in the <em>Scn5a</em><sup>+/-</sup> Mouse Model
Insecticidal Activity of the Essential Oils from Different Plants Against Three Stored-Product Insects
This study was conducted to determine the insecticidal activity of essential oils from oregano, Origanum onites L. (Lamiales: Lamiaceae), savory, Satureja thymbra L. (Lamiales: Lamiaceae), and myrtle, Myrtus communis L. (Rosales: Myrtaceae) against three stored-product insects. Essential oils from three species of plants were obtained by Clevenger-type water distillation. The major compounds in these essential oils were identified using gas chromatography-mass spectrometry and their insecticidal activity was tested against adults of the Mediterranean flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), the Indian meal moth Plodia interpunctella Hübner (Lepidoptera: Pyralidae) and the bean weevil Acanthoscelides obtectus Say (Coleoptera: Bruchidae). While the major compound found in oregano and savory was carvacrol, the main constituent of the myrtle was linalool. Among the tested insects, A. obtectus was the most tolerant species against the essential oils. However, the insecticidal activity of the myrtle oil was more pronounced than other oils tested against A. obtectus adults. The essential oils of oregano and savory were highly effective against P. interpunctella and E. kuehniella, with 100% mortality obtained after 24 h at 9 and 25 µl/l air for P. interpunctella and E. kuehniella, respectively. LC50 and LC99 values of each essential oil were estimated for each insect species
Multi-step optimization strategy for fuel-optimal orbital transfer of low-thrust spacecraft
Gene expression changes and community turnover differentially shape the global ocean metatranscriptome
Ocean microbial communities strongly influence the biogeochemistry, food webs, and climate of our planet. Despite recent advances in understanding their taxonomic and genomic compositions, little is known about how their transcriptomes vary globally. Here, we present a dataset of 187 metatranscriptomes and 370 metagenomes from 126 globally distributed sampling stations and establish a resource of 47 million genes to study community-level transcriptomes across depth layers from pole-to-pole. We examine gene expression changes and community turnover as the underlying mechanisms shaping community transcriptomes along these axes of environmental variation and show how their individual contributions differ for multiple biogeochemically relevant processes. Furthermore, we find the relative contribution of gene expression changes to be significantly lower in polar than in non-polar waters and hypothesize that in polar regions, alterations in community activity in response to ocean warming will be driven more strongly by changes in organismal composition than by gene regulatory mechanisms
Molecular Reclassification in Pediatric Osteosarcomas at Surgical Resection is a Potential Helpful Prognostic Marker
Variable Nav1.5 Protein Expression from the Wild-Type Allele Correlates with the Penetrance of Cardiac Conduction Disease in the Scn5a+/− Mouse Model
BACKGROUND: Loss-of-function mutations in SCN5A, the gene encoding Na(v)1.5 Na+ channel, are associated with inherited cardiac conduction defects and Brugada syndrome, which both exhibit variable phenotypic penetrance of conduction defects. We investigated the mechanisms of this heterogeneity in a mouse model with heterozygous targeted disruption of Scn5a (Scn5a(+/-) mice) and compared our results to those obtained in patients with loss-of-function mutations in SCN5A. METHODOLOGY/PRINCIPAL FINDINGS: Based on ECG, 10-week-old Scn5a(+/-) mice were divided into 2 subgroups, one displaying severe ventricular conduction defects (QRS interval>18 ms) and one a mild phenotype (QRS53 weeks), ajmaline effect was larger in the severely affected subgroup. These data matched the clinical observations on patients with SCN5A loss-of-function mutations with either severe or mild conduction defects. Ventricular tachycardia developed in 5/10 old severely affected Scn5a(+/-) mice but not in mildly affected ones. Correspondingly, symptomatic SCN5A-mutated Brugada patients had more severe conduction defects than asymptomatic patients. Old severely affected Scn5a(+/-) mice but not mildly affected ones showed extensive cardiac fibrosis. Mildly affected Scn5a(+/-) mice had similar Na(v)1.5 mRNA but higher Na(v)1.5 protein expression, and moderately larger I(Na) current than severely affected Scn5a(+/-) mice. As a consequence, action potential upstroke velocity was more decreased in severely affected Scn5a(+/-) mice than in mildly affected ones. CONCLUSIONS: Scn5a(+/-) mice show similar phenotypic heterogeneity as SCN5A-mutated patients. In Scn5a(+/-) mice, phenotype severity correlates with wild-type Na(v)1.5 protein expression
Genetic alterations in primary osteosarcoma from 54 children and adolescents by targeted allelotyping
- …