Magnetic topological semimetals allow for an effective control of the topological electronic states by tuning the spin configuration. Among them, Weyl nodal line semimetals are thought to have the greatest tunability, yet they are the least studied experimentally due to the scarcity of material candidates. Here, using a combination of angle-resolved photoemission spectroscopy and quantum oscillation measurements, together with density functional theory calculations, we identify the square-net compound EuGa as a magnetic Weyl nodal ring semimetal, in which the line nodes form closed rings near the Fermi level.
View Article and Find Full Text PDFWe overview the concept of dynamical phase transitions (DPTs) in isolated quantum systems quenched out of equilibrium. We focus on non-equilibrium transitions characterized by an order parameter, which features qualitatively distinct temporal behavior on the two sides of a certain dynamical critical point. DPTs are currently mostly understood as long-lived prethermal phenomena in a regime where inelastic collisions are incapable to thermalize the system.
View Article and Find Full Text PDFWe study quantum quenches of helical liquids with spin-flip inelastic scattering. Counterpropagating charge packets in helical edges can be created by an ultrashort electric pulse applied across a 2D topological insulator. Localized "hot spots" that form due to scattering enable two types of strongly nonlinear wave dynamics.
View Article and Find Full Text PDFIntegr Comp Biol
October 2021
Despite considerable research on lek-breeding birds, many aspects of the evolution of the lek social system, including the origin of male aggregation, remain unresolved. Originally, clusters may have formed passively as a by-product of independent but concurrent responses by males to some external stimulus (e.g.
View Article and Find Full Text PDFWe study the temperature dependence of the magnetic penetration depth in a 3D topological superconductor (TSC), incorporating the paramagnetic current due to the surface states. A TSC is predicted to host a gapless 2D surface Majorana fluid. In addition to the bulk-dominated London response, we identify a T^{3} power-law-in-temperature contribution from the surface, valid in the low-temperature limit.
View Article and Find Full Text PDFParticle fractionalization is believed to orchestrate the physics of many strongly correlated systems, yet its direct experimental detection remains a challenge. We propose a simple measurement for an ultracold matter system, in which correlations in initially decoupled 1D chains are imprinted via quantum quench upon two-dimensional Dirac fermions. Luttinger liquid correlations launch relativistic "fractionalization waves" along the chains, while coupling noninteracting chains induces perpendicular dispersion.
View Article and Find Full Text PDFWe present numerical evidence that most two-dimensional surface states of a bulk topological superconductor (TSC) sit at an integer quantum Hall plateau transition. We study TSC surface states in class CI with quenched disorder. Low-energy (finite-energy) surface states were expected to be critically delocalized (Anderson localized).
View Article and Find Full Text PDFIn two dimensions, dephasing by a bath cuts off Anderson localization that would otherwise occur at any energy density for fermions with disorder. For an isolated system with short-range interactions, the system can be its own bath, exhibiting diffusive (non-Markovian) thermal density fluctuations. We recast the dephasing of weak localization due to a diffusive bath as a self-interacting polymer loop.
View Article and Find Full Text PDFWe report the enhancement of the thermoelectric power (TEP) in graphene with extremely low disorder. At high temperature we observe that the TEP is substantially larger than the prediction of the Mott relation, approaching to the hydrodynamic limit due to strong inelastic scattering among the charge carriers. However, closer to room temperature the inelastic carrier-optical-phonon scattering becomes more significant and limits the TEP below the hydrodynamic prediction.
View Article and Find Full Text PDFThe combination of Rashba spin-orbit coupling and potential disorder induces a random current operator for the edge states of a 2D topological insulator. We prove that charge transport through such an edge is ballistic at any temperature, with or without Luttinger liquid interactions. The solution exploits a mapping to a spin 1/2 in a time-dependent field that preserves the projection along one randomly undulating component (integrable dynamics).
View Article and Find Full Text PDFWe show that two-terminal transport can measure the Luttinger liquid (LL) parameter K, in helical LLs at the edges of two-dimensional topological insulators (TIs) with Rashba spin-orbit coupling. We consider a Coulomb drag geometry with two coplanar TIs and short-ranged spin-flip interedge scattering. Current injected into one edge loop induces circulation in the second, which floats without leads.
View Article and Find Full Text PDFUltracold atomic gases in two dimensions tuned close to a p-wave Feshbach resonance were expected to exhibit topological superfluidity, but these were found to be experimentally unstable. We show that one can induce a topological Floquet superfluid if weakly interacting atoms are brought suddenly close ("quenched") to such a resonance, in the time before the instability kicks in. The resulting superfluid possesses Majorana edge modes, yet differs from a conventional Floquet system as it is not driven externally.
View Article and Find Full Text PDFNitrogen (N) enrichment of tropical reefs can result in the dominance of invasive algae. The invasive alga Acanthophora spicifera and the native alga Laurencia nidifica are part of a diverse reef assemblage in 'Ewa Beach, O'ahu. Their N contents and δ(15)N values were investigated to determine if N was enriched and to evaluate potential nitrogenous sources near and removed from storm-drain outlets.
View Article and Find Full Text PDFStorm-water drainage systems have potential to collect and focus nutrient enriched runoff into coastal systems. Storm-drain effluent could support macroalgal production and result in altered communities. To test this hypothesis, we assessed species composition and percent cover of native and non-native benthic macroalgae at eight intertidal sites along 'Ewa Beach, Hawai'i.
View Article and Find Full Text PDFWe show that arbitrarily weak interparticle interactions destabilize the surface states of 3D topological superconductors with spin SU(2) invariance (symmetry class CI) in the presence of nonmagnetic disorder. The conduit for the instability is disorder-induced wave function multifractality. We argue that time-reversal symmetry breaks spontaneously at the surface, so that topologically protected states do not exist for this class.
View Article and Find Full Text PDFWe study a quantum quench in a 1D system possessing Luttinger liquid (LL) and Mott insulating ground states before and after the quench, respectively. We show that the quench induces power law amplification in time of any particle density inhomogeneity in the initial LL ground state. The scaling exponent is set by the fractionalization of the LL quasiparticle number relative to the insulator.
View Article and Find Full Text PDFSubstance P (SP) and calcitonin gene-related peptide (CGRP) are well established mediators of inflammation. Therefore, inhibition of the biosynthesis of these neuropeptides is an attractive potential strategy for pharmacological intervention against a number of inflammatory diseases. The final step in the biosynthesis of SP and CGRP is the conversion of their glycine-extended precursors to the active amidated peptide, and this process is catalyzed by sequential action of the enzymes peptidylglycine alpha-monooxygenase (PAM) and peptidylamidoglycolate lyase.
View Article and Find Full Text PDFRecent studies have shown that the proliferation of some tumor cells is dependent on autocrine growth loops that require amidated autocrine growth factors. Peptidylglycine alpha-monooxygenase (PAM) is required for amidation of these growth factors and, therefore, this enzyme is an attractive target for anti-tumor compounds. 4-Phenyl-3-butenoic acid (PBA) is an irreversible turnover-dependent inhibitor of PAM in vitro and has been shown to decrease lung cancer cell proliferation by inhibiting the synthesis of amidated growth factors.
View Article and Find Full Text PDFFollowing B-cell antigen receptor (BCR) ligation, the cytoplasmic domains of immunoglobulin alpha (Ig alpha) and Ig beta recruit Syk to initiate signaling cascades. The coupling of Syk to several distal substrates requires linker protein BLNK. However, the mechanism by which BLNK is recruited to the BCR is unknown.
View Article and Find Full Text PDFPurpose: Garlic has been used as a flavouring agent, traditional medicine, and functional food to improve physical or mental well-being. Garlic and garlic products generally have been regarded as safe but a number of conflicting reports in the literature and confounding factors make it difficult to unequivocally establish the clinical efficacy and safety of these products either alone or in the presence of therapeutic products. A preliminary study was undertaken with fresh garlic and garlic products using the major cDNA-expressed human cytochrome P-450 isozymes associated with the metabolism of HIV/AIDS drugs, and purified P-glycoprotein (P-gp) cell membranes to ascertain the risk potential for generating interactions with therapeutic products.
View Article and Find Full Text PDFFEMS Microbiol Lett
March 1994
Under low-iron conditions, Escherichia coli synthesizes the siderophore enterobactin. When compared to wild-type cells grown in iron sufficient medium, cells grown under iron limitation, in the absence of tyrosine and phenylalanine or the presence of both, increased catechol production (a measure of enterobactin and its degradation product 2,3-dihydroxybenzoic acid) 5- to 9-fold while cells supplemented with tyrosine alone produced a 10- to 20-fold increase. Mutations in fur, tyrA, pheA, or pheU generally resulted in increased enterobactin production, while a tyrR mutant was unaffected by combinations of tyrosine and phenylalanine.
View Article and Find Full Text PDFThe strictly anaerobic, extremely thermophilic methanogens, Methanobacterium thermoautotrophicum Marburg and M. thermoautotrophicum delta H, have been cultivated in liquid culture and on solid medium in screw-top bottles, which permit continuous monitoring of the growth of the microorganisms. We have been able to routinely grow methanogens in medium containing bicarbonate, TRIS or 4-morpholinepropanesulfonic acid (MOPS) buffers and three different sulfur sources (sulfide, sulfite and thiosulfate) at temperatures up to 70 degrees C and at pressures up to 35 psi while monitoring cell density or colony formation.
View Article and Find Full Text PDFLong-tailed manakins (Chiroxiphia linearis) and swallow-tailed manakins (C. caudata) are closely related, sexually dichromatic, lek-breeding species in which male mating success is highly skewed. Males of both species delay plumage maturation.
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