Utilizing spin‐orbit torque (SOT) to switch a magnetic moment provides a promising route for low‐power‐dissipation spintronic devices. Here, the SOT switching of a nearly compensated ferrimagnet ...Gdx(FeCo)1−x by the topological insulator Bi2Se3 and (BiSb)2Te3 is investigated at room temperature. The switching current density of (BiSb)2Te3 (1.20 × 105 A cm−2) is more than one order of magnitude smaller than that in conventional heavy‐metal‐based structures, which indicates the ultrahigh efficiency of charge‐spin conversion (>1) in topological surface states. By tuning the net magnetic moment of Gdx(FeCo)1−x via changing the composition, the SOT efficiency has a significant enhancement (6.5 times) near the magnetic compensation point, and at the same time the switching speed can be as fast as several picoseconds. Combining the topological surface states and the nearly compensated ferrimagnets provides a promising route for practical energy‐efficient and high‐speed spintronic devices.
Spin‐momentum locking in topological surface states promises ultrahigh spin‐orbit torque efficiency compared to bulk spin‐orbit coupling, where the energy dissipation can be reduced by one to two orders of magnitude. At the same time, near the magnetic compensation point of ferrimagnets, the spin‐orbit torque efficiency can be significantly enhanced.
State Taxes and Spatial Misallocation FAJGELBAUM, PABLO D.; MORALES, EDUARDO; SERRATO, JUAN CARLOS SUÁREZ ...
The Review of economic studies,
01/2019, Letnik:
86, Številka:
1 (306)
Journal Article
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We study state taxes as a potential source of spatial misallocation in the U.S.. We build a spatial general equilibrium framework that incorporates salient features of the U.S. state tax system, and ...use changes in state tax rates between 1980 and 2010 to estimate the model parameters that determine how worker and firm location respond to changes in state taxes. We find that heterogeneity in state tax rates leads to aggregate welfare losses. In terms of consumption equivalent units, harmonizing state taxes increases worker welfare by 0.6% if government spending is held constant, and by 1.2% if government spending responds endogenously. Harmonization of state taxes within Census regions achieves most of these gains. We also use our model to study the general equilibrium effects of recently implemented and proposed tax reforms.
The electrochemical oxygen reduction reaction is the limiting half-reaction for low-temperature hydrogen fuel cells, and currently costly Pt-based electrocatalysts are used to generate adequate ...rates. Although most other metals are not stable in typical acid-mediated cells, alkaline environments permit the use of less costly electrodes, such as silver. Unfortunately, monometallic silver is not sufficiently active for economical fuel cells. Herein we demonstrate the design of low-cost Ag-Co surface alloy nanoparticle electrocatalysts for oxygen reduction. Their performance relative to that of Pt is potential dependent, but reaches over half the area-specific activity of Pt nanoparticle catalysts and is more than a fivefold improvement over pure silver nanoparticles at typical operating potentials. The Ag-Co electrocatalyst was initially identified with quantum chemical calculations and then synthesized using a novel technique that generates a surface alloy, despite bulk immiscibility of the constituent materials. Characterization studies support the hypothesis that the activity improvement comes from a ligand effect, in which cobalt atoms perturb surface silver sites.
The ease of generating induced pluripotent stem (iPS) cells, and possibly their properties after reprogramming, depends on the origin of the somatic cell starting population. Reprogramming of ...keratinocytes is both faster and more efficient compared with fibroblasts, although more care is required when isolating, culturing and infecting these cells. In this study, we describe detailed protocols using both feeder-dependent and defined serum- and feeder-free conditions for culturing human keratinocytes from foreskin samples and punch biopsies, as well as how to isolate keratinocytes from plucked hair. We further describe culture techniques and approaches to efficiently infect and reprogram these cells for the purpose of generating iPS cells. The procedure of deriving keratinocytes takes 10-14 d, whereas reprogramming and the appearance of iPS cell colonies that can be isolated and established requires another 3-4 weeks.
Mutations in the IDH1 and IDH2 genes encoding isocitrate dehydrogenases are frequently found in human glioblastomas and cytogenetically normal acute myeloid leukaemias (AML). These alterations are ...gain-of-function mutations in that they drive the synthesis of the ‘oncometabolite’ R-2-hydroxyglutarate (2HG). It remains unclear how IDH1 and IDH2 mutations modify myeloid cell development and promote leukaemogenesis. Here we report the characterization of conditional knock-in (KI) mice in which the most common IDH1 mutation, IDH1(R132H), is inserted into the endogenous murine Idh1 locus and is expressed in all haematopoietic cells (Vav-KI mice) or specifically in cells of the myeloid lineage (LysM-KI mice). These mutants show increased numbers of early haematopoietic progenitors and develop splenomegaly and anaemia with extramedullary haematopoiesis, suggesting a dysfunctional bone marrow niche. Furthermore, LysM-KI cells have hypermethylated histones and changes to DNA methylation similar to those observed in human IDH1- or IDH2-mutant AML. To our knowledge, our study is the first to describe the generation and characterization of conditional IDH1(R132H)-KI mice, and also the first report to demonstrate the induction of a leukaemic DNA methylation signature in a mouse model. Our report thus sheds light on the mechanistic links between IDH1 mutation and human AML.
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Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Magnetic skyrmions are topologically nontrivial spin textures which hold great promise as stable information carriers in spintronic devices at the nanoscale. One of the major challenges for ...developing novel skyrmion-based memory and logic devices is fast and controlled creation of magnetic skyrmions at ambient conditions. Here we demonstrate controlled generation of skyrmion bubbles and skyrmion bubble lattices from a ferromagnetic state in sputtered ultrathin magnetic films at room temperature by a single ultrafast (35 fs) laser pulse. The skyrmion bubble density increases with the laser fluence, and it finally becomes saturated, forming disordered hexagonal lattices. Moreover, we present that the skyrmion bubble lattice configuration leads to enhanced topological stability as compared to isolated skyrmions, suggesting its promising use in data storage. Our findings shed light on the optical approach to the skyrmion bubble lattice in commonly accessible materials, paving the road toward the emerging skyrmion-based memory and synaptic devices.
New heterocyclic diradicaloids based on boron and nitrogen-doped polycyclic systems with open-shell ground-states are obtained via concomitant structural and quinoidal extensions, thus allowing to ...merge the best of both design strategies. A combination of experimental characterization and theoretical calculations have helped disclose their electronic structure, as well as rationalize their associated magnetic and photophysical properties, spanning the chemical space of available molecular templates for cutting-edge applications in organic electronics and spintronics.
In the adsorption literature, the Van't Hoff equation is used in different manners without any criteria about the concepts of physical-chemistry of equilibrium for calculation of thermodynamic ...parameters of adsorption. Indeed, the equilibrium constant (K) should be dimensionless for being used in the Van't Hoff equation. However, this is not a simple adjustment of units, as being spread in the literature, to become K dimensionless. In this paper, it will be calculated the equilibrium constants using numeric examples and show the flaws of the thermodynamics calculations, when the value of K is wrongly calculated, and what are the expected results of the changes in enthalpy (ΔH°) and changes in the entropy (ΔS°) that are spread in the literature.
•Determination of thermodynamic parameters by using Van't Hoof equation.•The correct equilibrium constant for determination of thermodynamic parameters of adsorption.•Use of nonlinear equilibrium isotherms at several temperatures to obtain the K.
Embryonic pluripotency can be recapitulated in vitro by a spectrum of pluripotent stem cell states stabilized with different culture conditions. Their distinct spatiotemporal characteristics provide ...an unprecedented tool for the study of early human development. The newly unveiled ability of some stem cell types for crossing xeno-barriers will facilitate the generation of interspecies chimeric embryos from distant species, including humans. When combined with efficient zygote genome editing technologies, xenogeneic human pluripotent stem cells may also open new frontiers for regenerative medicine applications, including the possibility of generating human organs in animals via interspecies chimeric complementation.
In this Perspective, Wu and Izpisua Belmonte describe the distinct pluripotent states identified to date in both rodents and primates, including an analysis of their molecular features and functional properties. They also summarize previous work on interspecies chimeras and potential applications in regenerative medicine.
Extreme sea levels (ESLs) in Europe could rise by as much as one metre or more by the end of this century due to climate change. This poses significant challenges to safeguard coastal communities. ...Here we present a comprehensive analysis of economically efficient protection scenarios along Europe's coastlines during the present century. We employ a probabilistic framework that integrates dynamic simulations of all ESL components and flood inundation, impact modelling and a cost-benefit analysis of raising dykes. We find that at least 83% of flood damages in Europe could be avoided by elevating dykes in an economically efficient way along 23.7%-32.1% of Europe's coastline, specifically where high value conurbations exist. The European mean benefit to cost ratio of the investments varies from 8.3 to 14.9 while at country level this ranges between 1.6 and 34.3, with higher efficiencies for a scenario with high-end greenhouse gas emissions and strong socio-economic growth.
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