10,608 research outputs found
Pseudospin symmetry in supersymmetric quantum mechanics: Schr\"odinger equations
The origin of pseudospin symmetry (PSS) and its breaking mechanism are
explored by combining supersymmetry (SUSY) quantum mechanics, perturbation
theory, and the similarity renormalization group (SRG) method. The
Schr\"odinger equation is taken as an example, corresponding to the
lowest-order approximation in transforming a Dirac equation into a diagonal
form by using the SRG. It is shown that while the spin-symmetry-conserving term
appears in the single-particle Hamiltonian , the PSS-conserving term appears
naturally in its SUSY partner Hamiltonian . The eigenstates of
Hamiltonians and are exactly one-to-one identical except for
the so-called intruder states. In such a way, the origin of PSS deeply hidden
in can be traced in its SUSY partner Hamiltonian . The
perturbative nature of PSS in the present potential without spin-orbit term is
demonstrated by the perturbation calculations, and the PSS-breaking term can be
regarded as a very small perturbation on the exact PSS limits. A general
tendency that the pseudospin-orbit splittings become smaller with increasing
single-particle energies can also be interpreted in an explicit way.Comment: 31 pages, 11 figures, 2 table
Nernst Effect and Superconducting Fluctuations in Zn-doped YBaCuO
We report the measurements of in-plane resistivity, Hall effect, and Nernst
effect in Zn doped YBaCuO epitaxial thin films grown
by pulsed laser deposition technique. The pseudogap temperature, ,
determined from the temperature dependence of resistivity, does not change
significantly with Zn doping. Meanwhile the onset temperature () of
anomalous Nernst signal above , which is interpreted as evidence for
vortex-like excitations, decreases sharply as the superconducting transition
temperature does. A significant decrease in the maximum of vortex
Nernst signal in mixed state is also observed, which is consistent with the
scenario that Zn impurities cause a decrease in the superfluid density and
therefore suppress the superconductivity. The phase diagram of ,
, and versus Zn content is presented and discussed.Comment: 6 pages, 5 figures, Latex; v2: to be published in PR
Activation of NF-κ B signalling pathway by inflammatory regulators and associated drug discovering
Intracellular signalling transduction plays a pivotal role in cell activation,and the regulation of gene transcription needs the involvement of series of nuclear factors. Nuclear transcription factor- kappa B, one of the key factors in mediating gene expression, takes an essential part in a body of physiological and pathological processes. Endotoxin lipopolysaccharides, proinflammatory cytokine tumor necrosis factor-alpha, liganddependent immunocellular B cell receptor and inflammation-associated bradykinin are four typical NF-κB activation pathways. Activating or inhibitory drugs focused on NF-κB maybe strongly related with the therapy of associated diseases, and the exploration of effective and economical drugs concentrated on NF-κB is crucial.KEY WORDS: Nuclear factor-κB; Inhibitor factor-κB; Inflammatory signalling; Drug discover
Activation of NF-ê B signalling pathway by inflammatory regulators and associated drug discovering
Intracellular signalling transduction plays a pivotal role in cell activation,and the regulation of gene transcription needs the involvement of series of nuclear factors. Nuclear transcription factor- kappa B, one of the key factors in mediating gene expression, takes an essential part in a body of physiological and pathological processes. Endotoxin lipopolysaccharides, proinflammatory cytokine tumor necrosis factor-alpha, liganddependent immunocellular B cell receptor and inflammation-associated bradykinin are four typical NF-êB activation pathways. Activating or inhibitory drugs focused on NF-êB maybe strongly related with the therapy of associated diseases, and the exploration of effective and economical drugs concentrated on NF-êB is crucial
Social media big data-based research on the influencing factors of insomnia and spatiotemporal evolution
Insomnia is a prevalent sleep disorder that causes serious harm to individuals and society. It is closely linked to not only personal factors but also social, economic and other factors. This study explores the influencing factors and spatial differentiation of insomnia from the perspective of social media. This paper chose China’s largest social media platform, Sina Weibo, as its data source. Then, based on the collected relevant data of 288 Chinese cities from 2013 to 2017, it explored the impact of economic, social, and environmental factors and an educated population on insomnia. Additionally, the importance and interaction of each influencing factor were analyzed. According to the results, the gross domestic product (GDP), proportion of households connected to the Internet and number of students in regular institutions of higher education are the major factors that influence insomnia, and their influences show obvious spatial nonstationarity. Rapid GDP growth has increased the probability of insomnia, and the positive correlation between the proportion of households connected to the internet and insomnia has strengthened annually. Although the impact of insomnia on college students decreased in some regions, the overall impact was still increasing annually, and spatial nonstationarity was obvious. Properly controlling GDP growth and unnecessary time spent online and guiding people to develop healthy Internet surfing habits and lifestyles will help improve their sleep quality. Our research results will help relevant professionals better understand the distribution of regional insomnia and provide a reference for related departments to formulate regional insomnia prevention and treatment policies
Global Sulfur Dioxide Emissions and the Driving Forces
The presence of sulfur dioxide (SO_{2}) in the air is a global concern because of its severe environmental and public health impacts. Recent evidence from satellite observations shows rapid changes in the spatial distribution of global SO_{2} emissions, but such features are generally missing in global emission inventories that use a bottom-up method due to the lack of up-to-date information, especially in developing countries. Here, we rely on the latest data available on emission activities, control measures, and emission factors to estimate global SO2 emissions for the period 1960–2014 on a 0.1° × 0.1° spatial resolution. We design two counterfactual scenarios to isolate the contributions of emission activity growth and control measure deployment on historical SO_{2} emission changes. We find that activity growth has been the major factor driving global SO_{2} emission changes overall, but control measure deployment is playing an increasingly important role. With effective control measures deployed in developed countries, the predominant emission contributor has shifted from developed countries in the early 1960s (61%) to developing countries at present (83%). Developing countries show divergency in mitigation strategies and thus in SO_{2} emission trends. Stringent controls in China are driving the recent decline in global emissions. A further reduction in SO_{2} emissions would come from a large number of developing nations that currently lack effective SO_{2} emission controls
High-mass star formation in the nearby region G352.630-1.067. I. parallax
Young or forming high-mass stars that are nearby and not within a cluster environment have the potential to provide fundamental insights into star formation. In this paper we report such a candidate (G352.630-1.067), for which we have measured the distance through very long baseline interferometry parallax observations of the associated 6.7 GHz class II methanol maser. We determine the distance to the source to be 0.69 -0.08 +0.10 kpc, which makes it the second nearest highmass star formation region (HMSFR) known, with only the Orion Nebula being closer. This may place this source, not within a Galactic spiral arm, but in the region between the Local and Sagittarius arms, indicating that molecular clouds in interarm regions may also generate high-mass stars. Kinematic association between this source and the Sagittarius Arm suggests that it may be located in a spur extending outward from this arm. Comparison with the known, nearby HMSFRs (distances less than 1 kpc), reveal that G352.630-1.067 is in a more isolated environment than others, hence providing an excellent candidate for investigations of the processes that form individual high-mass stars. We find a good spatial correlation between the 6.7 GHz methanol maser and high angular resolution images of the infrared outflow, suggesting that the class II methanol masers are closely associated with a jet/outflow in this source. © 2019 The American Astronomical Society.We thank the anonymous referee for helpful comments that improved the manuscript. This work was supported by the National Natural Science Foundation of China (11590781, 11873002, 11590780), Australian Research Council Discovery project number DP180101061 funded by the Australian Government, and the major scientific research project of Guangdong regular institutions of higher learning (2017KZDXM062)
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