8,966 research outputs found
Time-Reversal Invariant Topological Moir\'e Flatband: A Platform for the Fractional Quantum Spin Hall Effect
Motivated by recent experimental observation of the quantum spin Hall effect
in monolayer germanene, we study the topological phases of twisted bilayer
Kane-Mele model with time-reversal symmetry and spin conservation. For
large twist angles the helical edge states from the two layers are unstable and
the system is a trivial insulator. At small twist angles however, the emergent
moir\'e flatbands can be topologically nontrivial due to inversion symmetry
breaking from coupling to substrate. Each of these flatbands for each spin
projection admits a lowest-Landau-level description in the chiral limit and at
magic twist angle. This allows for the construction of a many-body Laughlin
state with time-reversal symmetry which can be stabilized by a short-range
pseudopotential, and therefore serves as an ideal platform for realizing the
so-far elusive fractional quantum spin Hall effect with emergent spin-1/2 U(1)
symmetry
Persistent spin current in mesoscopic ferrimagnetic spin ring
Using a semiclassical approach, we study the persistent magnetization current
of a mesoscopic ferrimagnetic ring in a nonuniform magnetic field. At zero
temperature, there exists persistent spin current because of the quantum
fluctuation of magnons, similar to the case of an antiferromagnetic spin ring.
At low temperature, the current shows activation behavior because of the
field-induced gap. At higher temperature, the magnitude of the spin current is
proportional to temperature T, similar to the reported result of a
ferromagnetic spin ring.Comment: 6 pages, 3 figures, one more reference adde
Widespread translational control contributes to the regulation of Arabidopsis photomorphogenesis
Environmental light regulates and optimizes plant growth and development. Genomic profiling of polysome-associated mRNA reveals that light stimulates dramatic changes in translational regulation, which contribute more to light-induced gene expression changes than transcriptional regulation
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Update on antiarrhythmic drug pharmacology.
Cardiac arrhythmias constitute a major public health problem. Pharmacological intervention remains mainstay to their clinical management. This, in turn, depends upon systematic drug classification schemes relating their molecular, cellular, and systems effects to clinical indications and therapeutic actions. This approach was first pioneered in the 1960s Vaughan-Williams classification. Subsequent progress in cardiac electrophysiological understanding led to a lag between the fundamental science and its clinical translation, partly addressed by The working group of the European Society of Cardiology (1991), which, however, did not emerge with formal classifications. We here utilize the recent Revised Oxford Classification Scheme to review antiarrhythmic drug pharmacology. We survey drugs and therapeutic targets offered by the more recently characterized ion channels, transporters, receptors, intracellular Ca2+ handling, and cell signaling molecules. These are organized into their strategic roles in cardiac electrophysiological function. Following analysis of the arrhythmic process itself, we consider (a) pharmacological agents directly targeting membrane function, particularly the Na+ and K+ ion channels underlying depolarizing and repolarizing events in the cardiac action potential. (b) We also consider agents that modify autonomic activity that, in turn, affects both the membrane and (c) the Ca2+ homeostatic and excitation-contraction coupling processes linking membrane excitation to contractile activation. Finally, we consider (d) drugs acting on more upstream energetic and structural remodeling processes currently the subject of clinical trials. Such systematic correlations of drug actions and arrhythmic mechanisms at different molecular to systems levels of cardiac function will facilitate current and future antiarrhythmic therapy
Emergence of Chern Supermetal and Pair-Density Wave through Higher-Order Van Hove Singularities in the Haldane-Hubbard Model
While advances in electronic band theory have brought to light new
topological systems, understanding the interplay of band topology and
electronic interactions remains a frontier question. In this work, we predict
new interacting electronic orders emerging near higher-order Van Hove
singularities present in the Chern bands of the Haldane model. We classify the
nature of such singularities and employ unbiased renormalization group methods
that unveil a complex landscape of electronic orders, which include
ferromagnetism, density-waves and superconductivity. Importantly, we show that
repulsive interactions can stabilize long-sought pair-density wave state and an
exotic Chern supermetal, which is a new class of non-Fermi liquid with
anomalous quantum Hall response. This framework opens a new path to explore
unconventional electronic phases in two-dimensional chiral bands through the
interplay of band topology and higher-order Van Hove singularities.Comment: 6 pages; 3 figure
Collapses and revivals of exciton emission in a semiconductor microcavity: detuning and phase-space filling effects
We investigate exciton emission of quantum well embedded in a semiconductor
microcavity. The analytical expressions of the light intensity for the cases of
excitonic number state and coherent state are presented by using secular
approximation. Our results show that the effective exciton-exciton interaction
leads to the appearance of collapse and revival of the light intensity. The
revival time is twice compared the coherent state case with that of the number
state. The dissipation of the exciton-polariton lowers the revival amplitude
but does not alter the revival time. The influences of the detuning and the
phase-space filling are studied. We find that the effect of the higher-order
exciton-photon interaction may be removed by adjusting the detuning.Comment: 7 pages, 3 figure
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