236 research outputs found
An interesting example for spectral invariants
In "Illinois J. of Math. {\bf 38} (1994) 653--678", the heat operator of a
Bismut superconnection for a family of generalized Dirac operators is defined
along the leaves of a foliation with Hausdorff groupoid. The Novikov-Shubin
invariants of the Dirac operators were assumed greater than three times the
codimension of the foliation. It was then showed that the associated heat
operator converges to the Chern character of the index bundle of the operator.
In "J. K-Theory {\bf 1} (2008) 305--356", we improved this result by reducing
the requirement on the Novikov-Shubin invariants to one half of the
codimension. In this paper, we construct examples which show that this is the
best possible result.Comment: Third author added. Some typos corrected and some material added.
Appeared in Journal of K Theory, Volume 13, in 2014, pages 305 to 31
Exosomes and their Cargo as a New Avenue for Brain and Treatment of CNSRelated Diseases
Extracellular Vesicles (EVs), which belong to nanoscale vesicles, including microvesicles (MVs) and exosomes, are now considered a new important tool for intercellular neuronal communication in the Central Nervous System (CNS) under physiological and pathological conditions. EVs are shed into blood, peripheral body fluids and cerebrospinal fluid (CSF) by a large variety of cells. EVs can act locally on neighboring and distant cells. EVs represent the fingerprints of the originating cells and can carry a variety of molecular constituents of their cell of origin, including protein, lipids, DNA and microRNAs (miRNAs). The most studied EVs are the exosomes because they are ubiquitous and have the capacity to transfer cell-derived components and bioactive molecules to target cells. In this minireview, we focused on cell-cell communication in CNS mediated by exosomes and their important cargo as an innovative way to treat or follow up with CNS diseases. © 2022 Benameur et al
Extracellular vesicles miRNA cargo for microglia polarization in traumatic brain injury
Traumatic brain injury (TBI) is one of the major causes of death and disability worldwide, and despite its high dissemination, effective pharmacotherapies are lacking. TBI can be divided into two phases: the instantaneous primary mechanical injury, which occurs at the moment of insult, and the delayed secondary injury, which involves a cascade of biological processes that lead to neuroinflammation. Neuroinflammation is a hallmark of both acute and chronic TBI, and it is considered to be one of the major determinants of the outcome and progression of disease. In TBI one of the emerging mechanisms for cellâcell communication involved in the immune response regulation is represented by Extracellular Vesicles (EVs). These latter are produced by all cell types and are considered a fingerprint of their generating cells. Exosomes are the most studied nanosized vesicles and can carry a variety of molecular constituents of their cell of origin, including microRNAs (miRNAs). Several miRNAs have been shown to target key neuropathophysiological pathways involved in TBI. The focus of this review is to analyze exosomes and their miRNA cargo to modulate TBI neuroinflammation providing new strategies for prevent longâterm progression of disease
Kyste synovial intraosseux du scaphoĂŻde carpien bilatĂ©ral rĂ©vĂ©lĂ© par une fracture pathologique: Ă propos dâun cas et revu de la littĂ©rature
Nous rapportons l'observation d'un jeune patient qui présente un kyste synovial intraosseux (KSIO) du scaphoïde révélé par une fracture pathologique. Le kyste synovial intraosseux du scaphoïde constitue une étiologie trÚs rare des douleurs du poignet encore plus des fractures et la forme bilatérale associe à une fracture demeure une entité exceptionnelle, non décrite dans la littérature
Visibility of dichalcogenide nanolayers
Dichalcogenides with the common formula MX2 are layered materials with
electrical properties that range from semiconducting to superconducting. Here,
we describe optimal imaging conditions for optical detection of ultrathin,
two-dimensional dichalcogenide nanocrystals containing single, double and
triple layers of MoS2, WSe2 and NbSe2. A simple optical model is used to
calculate the contrast for nanolayers deposited on wafers with varying
thickness of SiO2. The model is extended for imaging using the green channel of
a video camera. Using AFM and optical imaging we confirm that single layers of
MoS2, WSe2 and NbSe2 can be detected on 90nm and 270 nm SiO2 using optical
means. By measuring contrast under broad-band green illumination we are also
able to distinguish between nanostructures containing single, mono and triple
layers of MoS2, WSe2 and NbSe2
L^2 rho form for normal coverings of fibre bundles
We define the secondary invariants L^2- eta and -rho forms for families of
generalized Dirac operators on normal coverings of fibre bundles. On the
covering family we assume transversally smooth spectral projections, and
Novikov--Shubin invariants bigger than 3(dim B+1) to treat the large time
asymptotic for general operators. In the particular case of a bundle of spin
manifolds, we study the L^2- rho class in relation to the space of positive
scalar curvature vertical metrics.Comment: 21 pages, revised versio
Impact strength of composites with nano-enhanced resin after fire exposure
Composite materials have been widely used in several engineering applications. However, there are very few studies about the effects of nanoclays on the impact strength of laminates after exposure to the fire. Therefore, this paper intends to study this subject and the impact performance was analysed by low velocity impact tests carried out at different incident impact energy levels. For better dispersion and interface adhesion matrix/clay, nanoclays were previously subjected to a silane treatment appropriate to the epoxy resin. The exposure to the fire decreases the maximum load and increases the displacement in comparison with the respective values obtained at room temperature. Mathematical relationships are proposed to estimate the maximum impact force and displacement, based on the total impact energy and flexural stiffness. Finally, a decrease of the elastic recuperation can be found, independently of the benefits introduced by the nanoclays
The emerging role of curcumin in the modulation of TLR-4 signaling pathway: Focus on neuroprotective and anti-rheumatic properties
Natural products have been used in medicine for thousands of years. Given their potential health benefits, they have gained significant popularity in recent times. The administration of phytochemicals existed shown to regulate differential gene expression and modulate various cellular pathways implicated in cell protection. Curcumin is a natural dietary polyphenol extracted from Curcuma Longa Linn with different biological and pharmacological effects. One of the important targets of curcumin is Toll-like receptor-4 (TLR-4), the receptor which plays a key role in the modulation of the immune responses and the stimulation of inflammatory chemokines and cytokines production. Different studies have demonstrated that curcumin attenuates inflammatory response via TLR-4 acting directly on receptor, or by its downstream pathway. Curcumin bioavailability is low, so the use of exosomes, as nano drug delivery, could improve the efficacy of curcumin in inflammatory diseases. The focus of this review is to explore the therapeutic effect of curcumin interacting with TLR-4 receptor and how this modulation could improve the prognosis of neuroinflammatory and rheumatic diseases
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