8,238 research outputs found
Liquid Crystal-Solid Interface Structure at the Antiferroelectric-Ferroelectric Phase Transition
Total Internal Reflection (TIR) is used to probe the molecular organization
at the surface of a tilted chiral smectic liquid crystal at temperatures in the
vicinity of the bulk antiferroelectric-ferroelectric phase transition. Data are
interpreted using an exact analytical solution of a real model for
ferroelectric order at the surface. In the mixture T3, ferroelectric surface
order is expelled with the bulk ferroelectric-antiferroelectric transition. The
conditions for ferroelectric order at the surface of an antiferroelectric bulk
are presented
Possible role of spinal astrocytes in maintaining chronic pain sensitization: review of current evidence with focus on bFGF/JNK pathway
Although pain is regarded traditionally as neuronally mediated, recent progress shows an important role of spinal glial cells in persistent pain sensitization. Mounting evidence has implicated spinal microglia in the development of chronic pain (e.g. neuropathic pain after peripheral nerve injury). Less is known about the role of astrocytes in pain regulation. However, astrocytes have very close contact with synapses and maintain homeostasis in the extracellular environment. In this review, we provide evidence to support a role of spinal astrocytes in maintaining chronic pain. In particular, c-Jun N-terminal kinase (JNK) is activated persistently in spinal astrocytes in a neuropathic pain condition produced by spinal nerve ligation. This activation is required for the maintenance of neuropathic pain because spinal infusion of JNK inhibitors can reverse mechanical allodynia, a major symptom of neuropathic pain. Further study reveals that JNK is activated strongly in astrocytes by basic fibroblast growth factor (bFGF), an astroglial activator. Intrathecal infusion of bFGF also produces persistent mechanical allodynia. After peripheral nerve injury, bFGF might be produced by primary sensory neurons and spinal astrocytes because nerve injury produces robust bFGF upregulation in both cell types. Therefore, the bFGF/JNK pathway is an important signalling pathway in spinal astrocytes for chronic pain sensitization. Investigation of signaling mechanisms in spinal astrocytes will identify new molecular targets for the management of chronic pain
Density Effect on Hadronization of a Quark Plasma
The hadronization cross section in a quark plasma at finite temperature and
density is calculated in the framework of Nambu--Jona-lasinio model with
explicit chiral symmetry breaking. In apposition to the familiar temperature
effect, the quark plasma at high density begins to hadronize suddenly. It leads
to a sudden and strong increase of final state pions in relativistic heavy ion
collisions which may be considered as a clear signature of chiral symmetry
restoration.Comment: Latex2e, 11 pages, 7 Postscript figures, submitted to Phys. Rev.
Angiogenesis-dependent and independent phases of intimal hyperplasia.
BACKGROUND: Neointimal vascular smooth muscle cell (VSMC) proliferation is a primary cause of occlusive vascular disease, including atherosclerosis, restenosis after percutaneous interventions, and bypass graft stenosis. Angiogenesis is implicated in the progression of early atheromatous lesions in animal models, but its role in neointimal VSMC proliferation is undefined. Because percutaneous coronary interventions result in induction of periadventitial angiogenesis, we analyzed the role of this process in neointima formation. METHODS AND RESULTS: Local injury to the arterial wall in 2 different animal models induced periadventitial angiogenesis and neointima formation. Application of angiogenesis stimulators vascular endothelial growth factor (VEGF-A165) or a proline/arginine-rich peptide (PR39) to the adventitia of the injured artery induced a marked increase in neointimal thickening beyond that seen with injury alone in both in vivo models. Inhibition of either VEGF (with soluble VEGF receptor 1 [sFlt1]) or fibroblast growth factor (FGF) (with a dominant=negative form of FGF receptor 1 [FGF-R1DN]), respectively, signaling reduced adventitial thickening induced by VEGF and PR39 to the level seen with mechanical arterial injury alone. However, neither inhibitor was effective in preventing neointimal thickening after mechanical injury when administered in the absence of angiogenic growth factor. CONCLUSIONS: Our findings indicate that adventitial angiogenesis stimulates intimal thickening but does not initiate it
A numerical study on dynamic shear rupture along frictional faults
The Wenchuan earthquake (Sichuan province, China, 2008) was caused by the dynamic rupture of Longmen Mountain fault. Such catastrophic disaster had led to a huge damage of life as well as major economic loss. The Longmen Mountain fault consisted of three faults with complex geometries, which gathered together as a main fault underground. The dynamic shear ruptures along the faults including bends and branches are frequently observed during earthquakes. In this study, the finite element method (FEM) is adopted to simulate the dynamic ruptures along both straight and branched faults, which are considered as frictional interfaces. A slip-weakening friction law is used to describe the interface behavior along faults. For the straight fault, the effects of pre-stress state and nucleation parameters on the dynamic shear rupture process are investigated; for the branched faults, the effects of pre-stress state and fault geometry on the rupture path selection are presented. The results are used to explain the rupture mechanism of Longmen Mountain fault during the earthquake
Rapid crack propagation in loosely fitted PE liner pipe
Published versio
Self-supervised Contrastive Video-Speech Representation Learning for Ultrasound
In medical imaging, manual annotations can be expensive to acquire and
sometimes infeasible to access, making conventional deep learning-based models
difficult to scale. As a result, it would be beneficial if useful
representations could be derived from raw data without the need for manual
annotations. In this paper, we propose to address the problem of
self-supervised representation learning with multi-modal ultrasound
video-speech raw data. For this case, we assume that there is a high
correlation between the ultrasound video and the corresponding narrative speech
audio of the sonographer. In order to learn meaningful representations, the
model needs to identify such correlation and at the same time understand the
underlying anatomical features. We designed a framework to model the
correspondence between video and audio without any kind of human annotations.
Within this framework, we introduce cross-modal contrastive learning and an
affinity-aware self-paced learning scheme to enhance correlation modelling.
Experimental evaluations on multi-modal fetal ultrasound video and audio show
that the proposed approach is able to learn strong representations and
transfers well to downstream tasks of standard plane detection and eye-gaze
prediction.Comment: MICCAI 2020 (early acceptance
Investigating the effects of steel slag powder on the properties of self-compacting concrete with recycled aggregates
This study introduced both steel slag and recycled aggregate aiming to improve the sustainability performance of self-compacting concrete (SCC). Study focused on investigating the effects of steel slag powder on the properties of
self-compacting concrete with recycled aggregate (SCRAC)
Enhancement of Transition Temperature in FexSe0.5Te0.5 Film via Iron Vacancies
The effects of iron deficiency in FexSe0.5Te0.5 thin films (0.8<x<1) on
superconductivity and electronic properties have been studied. A significant
enhancement of the superconducting transition temperature (TC) up to 21K was
observed in the most Fe deficient film (x=0.8). Based on the observed and
simulated structural variation results, there is a high possibility that Fe
vacancies can be formed in the FexSe0.5Te0.5 films. The enhancement of TC shows
a strong relationship with the lattice strain effect induced by Fe vacancies.
Importantly, the presence of Fe vacancies alters the charge carrier population
by introducing electron charge carriers, with the Fe deficient film showing
more metallic behavior than the defect-free film. Our study provides a means to
enhance the superconductivity and tune the charge carriers via Fe vacancy, with
no reliance on chemical doping.Comment: 15 pages, 4 figure
Unique white matter structural connectivity in early-stage drug-naive Parkinson disease
© 2019 American Academy of Neurology. OBJECTIVE: To investigate the topographic arrangement and strength of whole-brain white matter (WM) structural connectivity in patients with early-stage drug-naive Parkinson disease (PD). METHODS: We employed a model-free data-driven approach for computing whole-brain WM topologic arrangement and connectivity strength between brain regions by utilizing diffusion MRI of 70 participants with early-stage drug-naive PD and 41 healthy controls. Subsequently, we generated a novel group-specific WM anatomical network by minimizing variance in anatomical connectivity of each group. Global WM connectivity strength and network measures were computed on this group-specific WM anatomical network and were compared between the groups. We tested correlations of these network measures with clinical measures in PD to assess their pathophysiologic relevance. RESULTS: PD-relevant cortical and subcortical regions were identified in the novel PD-specific WM anatomical network. Impaired modular organization accompanied by a correlation of network measures with multiple clinical variables in early PD were revealed. Furthermore, disease duration was negatively correlated with global connectivity strength of the PD-specific WM anatomical network. CONCLUSION: By minimizing variance in anatomical connectivity, this study found the presence of a novel WM structural connectome in early PD that correlated with clinical symptoms, despite the lack of a priori analytic assumptions. This included the novel finding of increased structural connectivity between known PD-relevant brain regions. The current study provides a framework for further investigation of WM structural changes underlying the clinical and pathologic heterogeneity of PD
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