We show that the bulk-boundary correspondence for topological insulators can be modified in the presence of non-Hermiticity. We consider a one-dimensional tight-binding model with gain and loss as ...well as long-range hopping. The system is described by a non-Hermitian Hamiltonian that encircles an exceptional point in momentum space. The winding number has a fractional value of 1/2. There is only one dynamically stable zero-energy edge state due to the defectiveness of the Hamiltonian. This edge state is robust to disorder due to protection by a chiral symmetry. We also discuss experimental realization with arrays of coupled resonator optical waveguides.
We show that non-Hermitian dynamics generate substantial entanglement in many-body systems. We consider the non-Hermitian Lipkin-Meshkov-Glick model and show that its phase transition occurs with ...maximum multiparticle entanglement: There is full N-particle entanglement at the transition, in contrast to the Hermitian case. The non-Hermitian model also exhibits more spin squeezing than the Hermitian model, showing that non-Hermitian dynamics are useful for quantum metrology. Experimental implementations with trapped ions and cavity QED are discussed.
Quantum phase transitions are usually studied in terms of Hermitian Hamiltonians. However, cold-atom experiments are intrinsically non-Hermitian because of spontaneous decay. Here, we show that ...non-Hermitian systems exhibit quantum phase transitions that are beyond the paradigm of Hermitian physics. We consider the non-Hermitian XY model, which can be implemented using three-level atoms with spontaneous decay. We exactly solve the model in one dimension and show that there is a quantum phase transition from short-range order to quasi-long-range order despite the absence of a continuous symmetry in the Hamiltonian. The ordered phase has a frustrated spin pattern. The critical exponent ν can be 1 or 1/2 . Our results can be seen experimentally with trapped ions, cavity QED, and atoms in optical lattices.
The van der Pol oscillator is the prototypical self-sustained oscillator and has been used to model nonlinear behavior in biological and other classical processes. We investigate how quantum ...fluctuations affect phase locking of one or many van der Pol oscillators. We find that phase locking is much more robust in the quantum model than in the equivalent classical model. Trapped-ion experiments are ideally suited to simulate van der Pol oscillators in the quantum regime via sideband heating and cooling of motional modes. We provide realistic experimental parameters for 171Yb+ achievable with current technology.
We consider strongly interacting systems of effective spins, subject to dissipative spin-flip processes associated with optical pumping. We predict the existence of novel magnetic phases in the ...steady state of this system, which emerge due to the competition between coherent and dissipative processes. Specifically, for strongly anisotropic spin-spin interactions, we find ferromagnetic, antiferromagnetic, spin-density-wave, and staggered-XY steady states, which are separated by nonequilibrium phase transitions meeting at a Lifshitz point. These transitions are accompanied by quantum correlations, resulting in spin squeezing. Experimental implementations in ultracold atoms and trapped ions are discussed.
•A longitudinal study on trajectory of children's internalizing symptoms.•Chinese children develop internalizing symptoms into adolescence.•Parent–child relationship slower children from ...internalizing symptoms over time.•Sex is associated with internalizing symptoms over time.
Parenting and parental–child relationship may lead children to develop behavior disorders that can affect many aspects of their later life. This study aimed to examine the impact of parent–child relationship and sex on the development of internalizing symptoms in children.
Childhood and Adolescent Behaviors in Long-term Evolution (CABLE) is a longitudinal healthy-lifestyle research for which 18 elementary schools were randomly selected respectively in Taipei and Hsinchu in Taiwan. Data on sex, parent–child relations, and internalizing symptoms from four waves of follow-up were analyzed: 2003 (9 year olds), 2006 (12 year olds), 2009 (15 year olds) and 2012 (18 year olds). A latent growth model was used to examine the impact of parental–child relationship and sex on the trajectory of children's internalizing symptoms.
Results show that internalizing symptoms is more severe (β = 0.21, p < 0.01) and their growth rate faster (β = 0.15, p < 0.01) in girls than in boys. Results from latent growth model show that parent–child relationship is negatively related to the internalizing symptoms intercept (β = −0.59, p < 0.01) and is positively related to the internalizing symptoms slope (β = 0.18, p < 0.01). Limitations: Self-reported measures were used. Parent–child relationship was only provided at 2003.
The findings suggest that girls are more susceptible to internalizing symptoms in puberty, and better parent–child relationship can have a protective influence although the protective impact reduced through time. Health professionals should be sensitive to sex, family functioning and provide positive parenting programs for children at risk for internalizing symptoms.
Perivascular adipose tissue (PVAT)-derived relaxing factor (PVATRF) significantly regulates vascular tone. Its chemical nature remains unknown. We determined whether palmitic acid methyl ester (PAME) ...was the PVATRF and whether its release and/or vasorelaxing activity decreased in hypertension.
Using superfusion bioassay cascade technique, tissue bath myography, and gas chromatography/mass spectrometry, we determined PVATRF and PAME release from aortic PVAT preparations of Wistar Kyoto rats and spontaneously hypertensive rats. The PVAT of Wistar Kyoto rats spontaneously and calcium dependently released PVATRF and PAME. Both induced aortic vasorelaxations, which were inhibited by 4-aminopyridine (2 mmol/L) and tetraethylammonium 5 and 10 mmol/L but were not affected by tetraethylammonium 1 or 3 mmol/L, glibenclamide (3 μmol/L), or iberiotoxin (100 nmol/L). Aortic vasorelaxations induced by PVATRF- and PAME-containing Krebs solutions were not affected after heating at 70°C but were equally attenuated after hexane extractions. Culture mediums of differentiated adipocytes, but not those of fibroblasts, contained significant PAME and caused aortic vasorelaxation. The PVAT of spontaneously hypertensive rats released significantly less PVATRF and PAME with an increased release of angiotensin II. In addition, PAME-induced relaxation of spontaneously hypertensive rats aortic smooth muscle diminished drastically, which was ameliorated significantly by losartan.
We found that PAME is the PVATRF, causing vasorelaxation by opening voltage-dependent K+ channels on smooth muscle cells. Diminished PAME release and its vasorelaxing activity and increased release of angiotensin II in the PVAT suggest a noble role of PVAT in pathogenesis of hypertension. The antihypertensive effect of losartan is attributed partly to its reversing diminished PAME-induced vasorelaxation.
We study an open quantum system of atoms with a long-range Rydberg interaction, laser driving, and spontaneous emission. Over time, the system occasionally jumps between a state of low Rydberg ...population and a state of high Rydberg population. The jumps are inherently collective, and in fact, exist only for a large number of atoms. We explain how entanglement and quantum measurement enable the jumps, which are otherwise classically forbidden.
The article has two primary objectives: first, to elucidate why qualitative comparative analysis (QCA) stands out as a superior method for the study of groupthink, and second, to demonstrate the ...extent to which the Chinese leadership in 1989 fell prey to groupthink, resulting in ineffective decision-making that caused nationwide upheaval. While evidencing the causal connection between groupthink and the leadership group’s ineffective crisis management, the study nevertheless confirms the growing consensus that the groupthink model is over-specified. Accordingly, the article offers a revised model as a way to improve the groupthink theoretic constructs.
Microglia-mediated inflammation is implicated in pathogenesis of neurodegenerative diseases. Oroxylin A, a flavonoid isolated from Scutellariae baicalensis, has been shown to ameliorate microglia ...activation-mediated neurodegeneration in vivo. The molecular mechanism underlying the inhibitory effects of oroxylin A on microglia activation, however, remains unknown. In the present study, effects of oroxylin A co-treated with lipopolysaccharide (LPS, 100 ng/ml) on LPS-induced activation of cultured microglial BV-2 cells were examined. Nitric oxide (NO) production was determined by Greiss method. Expression of inducible nitric oxide synthase (iNOS), interleukin (IL)-1β and IL-6 was assessed using real-time RT-PCR or Western blot analysis. Furthermore, activation of the nuclear factor κB (NFκB) and the signal transducer and activator of transcription 1 (STAT1) was examined by Western blot analysis and transcription factor DNA-binding activity assay. Our results indicated that oroxylin A (10-100 µM) in a concentration-dependent manner inhibited LPS-induced NO production via blocking iNOS expression at both mRNA and protein levels without affecting the degradation rate of iNOS mRNA. Moreover, oroxylin A significantly attenuated LPS-induced late expression (20 hours after LPS challenge) of IL-1β and IL-6. Furthermore, oroxylin A significantly suppressed LPS-induced JAK2-mediated STAT1 phosphorylation without affecting LPS-induced NFκB-p65 nuclear translocation or NFκB-p65 DNA-binding activity. This is consistent with the finding that AG490, a specific JAK2 inhibitor, significantly inhibited LPS-induced STAT1 phosphorylation with almost completely diminished iNOS expression. These results suggest that oroxylin A, via suppressing STAT1 phosphorylation, inhibits LPS-induced expression of pro-inflammatory genes in BV-2 microglial cells.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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