7,840 research outputs found
Transversal Propagation Behaviors of Helical Edge States In a QSH System
The transversal propagation of the edge states in a two-dimensional quantum
spin Hall system are classified by decay characteristic quantity . Two
different modes of the helical edge states exhibit distinct behaviors. The
penetration depth is momentum dependent in normal edge states. The finite size
gap decays monotonously with sample width, leading to the normal size effect.
In contrast, the penetration depth maintains a uniform minimal value in the
special edge states with much shorter length. The finite size gap decays
non-monotonously with width, leading to the anomalous finite size effect. Real
materials are compared in the phase diagram, which explicitly demonstrates
their differences. We also propose an intuitive way to search the special edge
states in two-dimensional quantum spin Hall system.Comment: 6 pages, 4 figure
Pharmacological Basis for Use of Armillaria mellea
Armillaria mellea, an edible fungus, exhibits various pharmacological activities, including antioxidant and antiapoptotic properties. However, the effects of A. mellea on Alzheimer’s disease (AD) have not been systemically reported. The present study aimed to explore the protective effects of mycelium polysaccharides (AMPS) obtained from A. mellea, especially AMPSc via 70% ethanol precipitation in a L-glutamic acid- (L-Glu-) induced HT22 cell apoptosis model and an AlCl3 plus D-galactose- (D-gal-) induced AD mouse model. AMPSc significantly enhanced cell viability, suppressed nuclear apoptosis, inhibited intracellular reactive oxygen species accumulation, prevented caspase-3 activation, and restored mitochondrial membrane potential (MMP). In AD mice, AMPSc enhanced horizontal movements in an autonomic activity test, improved endurance times in a rotarod test, and decreased escape latency time in a water maze test. Furthermore, AMPSc reduced the apoptosis rate, amyloid beta (Aβ) deposition, oxidative damage, and p-Tau aggregations in the AD mouse hippocampus. The central cholinergic system functions in AD mice improved after a 4-week course of AMPSc administration, as indicated by enhanced acetylcholine (Ach) and choline acetyltransferase (ChAT) concentrations, and reduced acetylcholine esterase (AchE) levels in serum and hypothalamus. Our findings provide experimental evidence suggesting A. mellea as a neuroprotective candidate for treating or preventing neurodegenerative diseases
Treatment of Linear and Nonlinear Dielectric Property of Molecular Monolayer and Submonolayer with Microscopic Dipole Lattice Model: I. Second Harmonic Generation and Sum-Frequency Generation
In the currently accepted models of the nonlinear optics, the nonlinear
radiation was treated as the result of an infinitesimally thin polarization
sheet layer, and a three layer model was generally employed. The direct
consequence of this approach is that an apriori dielectric constant, which
still does not have a clear definition, has to be assigned to this polarization
layer. Because the Second Harmonic Generation (SHG) and the Sum-Frequency
Generation vibrational Spectroscopy (SFG-VS) have been proven as the sensitive
probes for interfaces with the submonolayer coverage, the treatment based on
the more realistic discrete induced dipole model needs to be developed. Here we
show that following the molecular optics theory approach the SHG, as well as
the SFG-VS, radiation from the monolayer or submonolayer at an interface can be
rigorously treated as the radiation from an induced dipole lattice at the
interface. In this approach, the introduction of the polarization sheet is no
longer necessary. Therefore, the ambiguity of the unaccounted dielectric
constant of the polarization layer is no longer an issue. Moreover, the
anisotropic two dimensional microscopic local field factors can be explicitly
expressed with the linear polarizability tensors of the interfacial molecules.
Based on the planewise dipole sum rule in the molecular monolayer, crucial
experimental tests of this microscopic treatment with SHG and SFG-VS are
discussed. Many puzzles in the literature of surface SHG and SFG spectroscopy
studies can also be understood or resolved in this framework. This new
treatment may provide a solid basis for the quantitative analysis in the
surface SHG and SFG studies.Comment: 23 pages, 3 figure
Probabilistic models for topic learning from images and captions in online biomedical literatures
Biomedical images and captions are one of the major sources of information in online biomedical publications. They often contain the most important results to be reported, and provide rich information about the main themes in published papers. In the data mining and information retrieval community, there are a lot of research works on using text mining and language modeling algorithms to extract knowledge from the text content of online biomedical publications; however, the problem of knowledge extraction from biomedical images and captions has not been fully studied yet. In this paper, a hierarchical probabilistic topic model with background distribution (HPB) is introduced to uncover the latent semantic topics from the co-occurrence patterns of caption words, visual words and biomedical concepts. With downloaded biomedical figures, restricted captions ar
The genetic diversity and evolutionary history of hepatitis C virus in Vietnam
AbstractVietnam has a unique history in association with foreign countries, which may have resulted in multiple introductions of the alien HCV strains to mix with those indigenous ones. In this study, we characterized the HCV sequences in Core-E1 and NS5B regions from 236 Vietnamese individuals. We identified multiple HCV lineages; 6a, 6e, 6h, 6k, 6l, 6o, 6p, and two novel variants may represent the indigenous strains; 1a was probably introduced from the US; 1b and 2a possibly originated in East Asia; while 2i, 2j, and 2m were likely brought by French explorers. We inferred the evolutionary history for four major subtypes: 1a, 1b, 6a, and 6e. The obtained Bayesian Skyline Plots (BSPs) consistently showed the rapid HCV population growth from 1955 to 1963 until 1984 or after, corresponding to the era of the Vietnam War. We also estimated HCV growth rates and reconstructed phylogeographic trees for comparing subtypes 1a, 1b, and HCV-2
A Distinct Difference between Air and Mucosal Temperatures in Human Respiratory Tract
xtensive evidence indicates that several types of temperature-sensitive ion channels are abundantly expressed in the sensory nerves innervating airway mucosa. Indeed, airway temperature is known to play an important role in regulating respiratory functions. However, the actual airway mucosal temperature and its dynamic changes during the respiratory cycle have not been directly measured. In previous studies, airway tissue temperature was often estimated by indirect measurement of the peak exhaled breath temperature (PEBT). In view of the poor thermal conductivity of air, we believe that the airway tissue temperature cannot be accurately determined by the exhaled air temperature, and this study aimed to test this hypothesis. We applied a miniature rapid-response temperature probe to measure directly the mucosal temperatures of trachea, major, lobar, and segmental bronchi in eight human subjects during a bronchoscopy procedure. Unlike the air temperature in the airway lumen, the mucosal temperature in these airway segments remained relatively stable and did not exhibit the phasic changes synchronous with respiratory cycles. The airway mucosal temperature increased progressively from the extra-thoracic trachea (35.7 ± 0.2°C) toward the segmental bronchus (36.9 ± 0.2°C). Most importantly, the temperatures measured directly at the mucosa of all these airway segments were substantially higher than the PEBT (31.7 ± 0.8°C). The recent findings of a close association between an increased PEBT and airway tissue inflammation have revealed the implication and potential of incorporating the PEBT measurement in the future clinical diagnosis of airway inflammation. Therefore, it is imperative to recognize this distinct difference in temperature between airway mucosa and exhaled air
On the group theoretic structure of a class of quantum dialogue protocols
Intrinsic symmetry of the existing protocols of quantum dialogue are
explored. It is shown that if we have a set of mutually orthogonal -qubit
states {\normalsize
and a set of
() unitary operators
and
forms a group under multiplication then it
would be sufficient to construct a quantum dialogue protocol using this set of
quantum states and this group of unitary operators}. The sufficiency condition
is used to provide a generalized protocol of quantum dialogue. Further the
basic concepts of group theory and quantum mechanics are used here to
systematically generate several examples of possible groups of unitary
operators that may be used for implementation of quantum dialogue. A large
number of examples of quantum states that may be used to implement the
generalized quantum dialogue protocol using these groups of unitary operators
are also obtained. For example, it is shown that GHZ state, GHZ-like state, W
state, 4 and 5 qubit Cluster states, Omega state, Brown state, state
and state can be used for implementation of quantum dialogue protocol.
The security and efficiency of the proposed protocol is appropriately analyzed.
It is also shown that if a group of unitary operators and a set of mutually
orthogonal states are found to be suitable for quantum dialogue then they can
be used to provide solutions of socialist millionaire problem.Comment: 15 page
Prediction of Giant Tunneling Magnetoresistance in RuO/TiO/RuO (110) Antiferromagnetic Tunnel Junctions
Using first-principles quantum-transport calculations, we investigate
spin-dependent electronic and transport properties of antiferromagnetic tunnel
junctions (AFMTJs) that consist of (110)-oriented antiferromagnetic (AFM) metal
RuO electrodes and an insulating TiO tunneling barrier. We predict
the emergence of a giant tunneling magnetoresistance (TMR) effect in a wide
energy window, a series of barrier layer thicknesses, and different interface
terminations, indicating the robustness of this effect. We show that the
predicted TMR cannot be explained in terms of the global transport
spin-polarization of RuO (110) but is well understood based on matching
the momentum-dependent spin-polarized conduction channels of the two RuO
(110) electrodes. We predict oscillations of TMR with increasing barrier
thickness, indicating a non-negligible contribution from the perfectly
epitaxial interfaces. Our work helps the understanding of the physics of TMR in
AFMTJs and aids in realizing efficient AFM spintronic devices
3D Histogram Based Anomaly Detection for Categorical Sensor Data in Internet of Things
The applications of Internet-of-things (IoT) deploy massive number of sensors to monitor the system and environment. Anomaly detection on streaming sensor data is an important task for IoT maintenance and operation. In real IoT applications, many sensors report categorical values rather than numerical readings. Unfortunately, most existing anomaly detection methods are designed only for numerical sensor data. They cannot be used to monitor the categorical sensor data. In this study, we design and develop a 3D Histogram based Categorical Anomaly Detection (HCAD) solution to monitor categorical sensor data in IoT. HCAD constructs the histogram model by three dimensions: categorical value, event duration, and frequency. The histogram models are used to profile normal working states of IoT devices. HCAD automatically determines the range of normal data and anomaly threshold. It only requires very limit parameter setting and can be applied to a wide variety of different IoT devices. We implement HCAD and integrate it into an online monitoring system. We test the proposed solution on real IoT datasets such as telemetry data from satellite sensors, air quality data from chemical sensors, and transportation data from traffic sensors. The results of extensive experiments show that HCAD achieves higher detecting accuracy and efficiency than state-of-the-art methods
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