1,985 research outputs found
Superconducting proximity effect to the block antiferromagnetism in KFeSe
Recent discovery of superconducting (SC) ternary iron selenides has block
antiferromagentic (AFM) long range order. Many experiments show possible
mesoscopic phase separation of the superconductivity and antiferromagnetism,
while the neutron experiment reveals a sizable suppression of magnetic moment
due to the superconductivity indicating a possible phase coexistence. Here we
propose that the observed suppression of the magnetic moment may be explained
due to the proximity effect within a phase separation scenario. We use a
two-orbital model to study the proximity effect on a layer of block AFM state
induced by neighboring SC layers via an interlayer tunneling mechanism. We
argue that the proximity effect in ternary Fe-selenides should be large because
of the large interlayer coupling and weak electron correlation. The result of
our mean field theory is compared with the neutron experiments
semi-quantitatively. The suppression of the magnetic moment due to the SC
proximity effect is found to be more pronounced in the d-wave superconductivity
and may be enhanced by the frustrated structure of the block AFM state.Comment: 6 pages, 6 figure
Theory for charge and orbital density-wave states in manganite LaSrMnO
We investigate the high temperature phase of layered manganites, and
demonstrate that the charge-orbital phase transition without magnetic order in
LaSrMnO can be understood in terms of the density wave
instability. The orbital ordering is found to be induced by the nesting between
segments of Fermi surface with different orbital characters. The simultaneous
charge and orbital orderings are elaborated with a mean field theory. The
ordered orbitals are shown to be .Comment: published versio
Quantized charge-pumping in higher-order topological insulators
We study the quantized charge pumping of higher-order topological insulators
(HOTIs) with edge-corner correspondences based on the combination of the
rotation of in-plane magnetic field and the quantum spin Hall effect. A picture
of a specific charge pumping process is uncovered with the help of the
non-equilibrium Green's function method. Significantly, we demonstrate that the
quantized charge pumping current is achieved without the participation of bulk
states, and the charges move along the boundary of the sample. Furthermore, the
effects of external parameters on the pumping current is also studied. We find
that the magnitude and direction of the pumping current can be manipulated by
adjusting the coupling strength between the leads and sample. Our work deepens
the understanding of the charge pumping in HOTIs and extends the study of their
transport properties.Comment: 8 pages, 5 figure
A developmental approach to robotic pointing via human–robot interaction
This is an open access article under the CC
BY license (http://creativecommons.org/licenses/by/3.0/)The ability of pointing is recognised as an essential skill of a robot in its communication and social interaction. This paper introduces a developmental learning approach to robotic pointing, by exploiting the interactions between a human and a robot. The approach is inspired through observing the process of human infant development. It works by first applying a reinforcement learning algorithm to guide the robot to create attempt movements towards a salient object that is out of the robot's initial reachable space. Through such movements, a human demonstrator is able to understand the robot desires to touch the target and consequently, to assist the robot to eventually reach the object successfully. The human-robot interaction helps establish the understanding of pointing gestures in the perception of both the human and the robot. From this, the robot can collect the successful pointing gestures in an effort to learn how to interact with humans. Developmental constraints are utilised to drive the entire learning procedure. The work is supported by experimental evaluation, demonstrating that the proposed approach can lead the robot to gradually gain the desirable pointing ability. It also allows that the resulting robot system exhibits similar developmental progress and features as with human infants
Deep Learning for Logo Detection: A Survey
When logos are increasingly created, logo detection has gradually become a
research hotspot across many domains and tasks. Recent advances in this area
are dominated by deep learning-based solutions, where many datasets, learning
strategies, network architectures, etc. have been employed. This paper reviews
the advance in applying deep learning techniques to logo detection. Firstly, we
discuss a comprehensive account of public datasets designed to facilitate
performance evaluation of logo detection algorithms, which tend to be more
diverse, more challenging, and more reflective of real life. Next, we perform
an in-depth analysis of the existing logo detection strategies and the
strengths and weaknesses of each learning strategy. Subsequently, we summarize
the applications of logo detection in various fields, from intelligent
transportation and brand monitoring to copyright and trademark compliance.
Finally, we analyze the potential challenges and present the future directions
for the development of logo detection to complete this survey
Assessing the utility of structure in amorphous materials
This paper presents a set of general strategies for the analysis of structure
in amorphous materials and a general approach to assessing the utility of a
selected structural description. Measures of structural diversity and utility
are defined and applied to two model glass forming binary atomic alloys. In
addition, a new measure of incipient crystal-like organization is introduced,
suitable for cases where the stable crystal is a compound structure
Elastoplastic Analysis of Circular Openings in Elasto-Brittle-Plastic Rock Mass Based on Logarithmic Strain
Rock-like materials, such as coal and soft rock, often manifest larger deformation features. The prediction values for displacement and failure region based on the commonly used small strain (SS) theory are generally larger than the field test results. Based on the Euler coordinate system, the logarithmic strain (LS) is employed to describe the actual deformation behavior. Both of the stresses and displacement of circular opening in elasto-brittle-plastic rock mass are formulated with differential equations. And a simple approach is proposed to solve the differential equations. The results show that the plastic radius depends on the elastic parameters, that is, Young’s modulus and Poisson’s ratio, which is different from SS theory. And the plastic radius and displacement of LS rock mass are smaller than those of SS rock mass, and the displacement of LS rock mass is absolutely smaller than the excavation radius. The proposed solutions can provide theoretical foundation for the optimization of supporting structure in underground engineering
(Benzoato-κ2 O,O′)(5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-κ4 N,N′,N′′,N′′′)nickel(II) perchlorate benzoic acid solvate
In the title compound, [Ni(C7H5O2)(C16H36N4)]ClO4·C7H6O2, the Ni atom displays a distorted octahedral coordination geometry with four N atoms of the ligand rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (L) in a folded configuration and two benzoate (bz) O atoms. The [Ni(rac-L)(bz)]+ complex cation, perchlorate anion and benzoic acid molecules engage in hydrogen bonding, with N⋯O distances between 2.970 (3) and 3.123 (3) Å and an O⋯O distance of 2.691 (3) Å
Leukotriene B4, administered via intracerebroventricular injection, attenuates the antigen-induced asthmatic response in sensitized guinea pigs
<p>Abstract</p> <p>Background</p> <p>Despite intensive studies focused on the pathophysiology of asthmatic inflammation, little is known about how cross-talk between neuroendocrine and immune systems regulates the inflammatory response during an asthmatic attack. We recently showed corresponding changes of cytokines and leukotriene B<sub>4 </sub>(LTB<sub>4</sub>) in brain and lung tissues of antigen-challenged asthmatic rats. Here, we investigated how LTB<sub>4 </sub>interacts with the neuroendocrine-immune system in regulating antigen-induced asthmatic responses in sensitized guinea pigs.</p> <p>Methods</p> <p>Ovalbumin-sensitized guinea pigs were challenged by inhalation of antigen. Vehicle, LTB<sub>4 </sub>or U75302 (a selective LTB<sub>4 </sub>BLT1 receptor inhibitor) was given via intracerebroventricular injection (i.c.v.) 30 min before challenge. Airway contraction response was evaluated using Penh values before and after antigen challenge. The inflammatory response in lung tissue was evaluated 24 h after challenge. The LTB<sub>4 </sub>content of lung and brain homogenate preparations was detected by reversed phase high-performance liquid chromatography (RP-HPLC). Plasma levels of adrenocorticotropic hormone (ACTH) and corticosterone (CORT) were measured using ELISA kits.</p> <p>Results</p> <p>Antigen challenge impaired pulmonary function and increased inflammatory cell infiltration in lung tissue. These responses could be significantly suppressed by LTB<sub>4</sub>, 30 ng i.c.v., in ovalbumin-sensitized guinea pigs. LTB<sub>4 </sub>content of lung and brain homogenates from antigen-challenged guinea pigs was significantly increased. In addition, administration of LTB<sub>4 </sub>via i.c.v. markedly increased CORT and ACTH level in plasma before antigen challenge, and there were further increases in CORT and ACTH levels in plasma after antigen challenge. U75302, 100 ng i.c.v., completely blocked the effects of LTB<sub>4</sub>. In addition, U75302, 100 ng via i.c.v. injection, markedly decreased LTB<sub>4 </sub>content in lung homogenates, but not in brain homogenates.</p> <p>Conclusions</p> <p>Increased LTB<sub>4 </sub>levels in brain during asthmatic attacks down-regulates airway contraction response and inflammation through the BLT1 receptor. Stimulation of the hypothalamic-pituitary-adrenal axis by LTB<sub>4 </sub>may result in an increase in systemic glucocorticoids which, in turn, would feed back to suppress the asthmatic response.</p
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