173,270 research outputs found
Parameterized strict deformation quantization of C*-bundles and Hilbert C*-modules
No full textIn this paper, we review the parametrized strict deformation quantization of C*-bundles obtained in a previous paper, and give more examples and applications of this theory. In particular, it is used here to classify H3-twisted noncommutative torus bundles over a locally compact space. This is extended to the case of general torus bundles and their parametrized strict deformation quantization. Rieffel’s basic construction of an algebra deformation can be mimicked to deform a monoidal category, which deforms not only algebras but also modules. As a special case, we consider the parametrized strict deformation quantization of Hilbert C*-modules over C*-bundles with fibrewise torus action.Keith C. Hannabuss and Varghese Matha
C*-algebras in tensor categories
No full textWe define and systematically study nonassociative C*-algebras as C*-algebras
internal to a topological tensor category. We also offer a concrete approach to
these C*-algebras, as G-invariant, norm closed *-subalgebras of bounded
operators on a G-Hilbert space, with deformed composition product. Our central
results are those of stabilization and Takai duality for (twisted) crossed
products in this context.Peter Bouwknegt, Keith C. Hannabuss, and Varghese Matha
Biomineralized materials as bone ECM mimetics: From understanding molecular mechanisms to new therapeutic interventions
No full textBone extracellular matrix is a heterogeneous composite material consisting, of an inorganic (or mineral) phase, an organic phase and water. In an effort to mimic the mineral environment of bone tissue, we recently employed biomineralization and created mineralized biomaterials (1). Our studies showed that these biomineralized materials induced osteogenic differentiation of stem cells, including human pluripotent stem cells (which includes both embryonic stem cells and induced pluripotent stem cells), even in growth medium devoid of any osteogenic inducing molecules (2,3). By employing these mineralized materials, we have studied the molecular mechanism through which calcium phosphate minerals support osteogenesis with an emphasis on phosphate metabolism (4). Our studies show that extracellular phosphate (resulting from the dissolution of calcium phosphate minerals) uptake through solute carrier family 20 phosphate transporter member 1 (SLC20a1) supports osteogenic differentiation of human mesenchymal stem cells via adenosine, an ATP metabolite, which acts as an autocrine/paracrine signaling molecule through A2b adenosine receptor. Perturbation of SlC20a1 abrogates osteogenic differentiation by decreasing intra-mitochondrial phosphate and ATP synthesis. Our studies further show that the phosphate-ATP-adenosine signaling axis not only promotes osteogenic differentiation of multipotent progenitor cells but also inhibits their adipogenic differentiation (5). When implanted in vivo, these acellular mineralized biomaterials recruited endogenous cells and induced their differentiation to form vascularized bone tissues (6) and also supported donor bone marrow transplantation (7). Leveraging these understandings, we are currently studying the pivotal role of Adenosine A2b receptor, a G-protein coupled receptor on the cell membrane, in regulating bone-specific cells and treating bone metabolic disorders. In this talk, I will discuss these results and the identification of possible drug targets for osteoporosis.
REFERENCES
[1] Phadke A, Zhang C, Hwang YS, Vecchio K, Varghese S. “Templated mineralization of synthetic hydrogels for bone like composite material: Role of matrix hydrophobicity”, Biomacromolecules. 2010; 11, 2060
[2] Phadke A, Shig Y-R, Varghese, S. “Mineralized synthetic matrices as an instructive microenvironment for osteogenic differentiation of human mesenchymal stem cells” Macromol Biosci. 2012, 12, 1022
[3] Kang H, Shih Y-RV, Hwang YS, Wen C, Rao V, Seo T, and Varghese S. “Mineralized gelatin methacrylate-based matrices induce osteogenic differentiation of human induced pluripotent stem cells” Acta Biomater. 2014, 10, 4961
[4] Shih Y-RV, Hwang YS, Phadke A, Kang H, Hwang NS, Caro EJ, Nguyen S, Siu M, Theodorakis EA, Gianneschi NC, Vecchio KS, Chien S, Lee OK and Varghese S. “Calcium phosphate-bearing matrices induce osteogenic differentiation of stem cells through adenosine signaling” Proc. Natl. Acad. Sci. 2014, 111, 990.
[5] Kang H, Shih Y-RV, Varghese S. “Biomineralized matrices dominate soluble cues to direct osteogenic differentiation of human mesenchymal stem cells through adenosine signaling” Biomacromolecules 2015, 16, 1050
[6] Shih Y-RV, Phadke A, Yamaguchi T, Kang H, Inoue N, Masuda K and Varghese S. “Synthetic bone mimetic matrix-mediated in situ bone tissue formation through host cell recruitment” Acta Biomater. 2015, 19, 1.
[7] Shih Y-RV, Kang H, Rao V, Chu Y-J, Kown SK, and Varghese S. “In vivo engineering of bone organoids with hematopoietic functions” Proc. Natl. Acad. Sci, 2017, 114, 5419
Noncommutative principal torus bundles via parametrised strict deformation quantization
No full textIn this paper, we initiate the study of a parametrised version of Fieffel's strict deformation quantization. We apply it to give a classification of noncommutative prinicpal torus bundles, in terms of parametrised strict deformation quantization of ordinary principal torus bundles. The paper also contains a putative defination of noncommutative non-principal torus bundles.Keith C. Hannabuss and Varghese Matha
Nonassociative strict deformation quantization of C*-algebras and nonassociative torus bundles
No full textIn this paper, we initiate the study of nonassociative strict deformation quantization of C∗-algebras with a torus action. We shall also present a definition of nonassociative principal torus bundles, and give a classification of these as nonassociative strict deformation quantization of ordinary principal torus bundles. We then relate this to T-duality of principal torus bundles with H-flux. In particular, the Octonions fit nicely into our theory.Keith C. Hannabuss, Varghese Matha
D-Branes, B-Fields and twisted K-theory
No full textCopyright © Institute of Physics and IOP Publishing LimitedIn this note we propose that D-brane charges, in the presence of a topologically non-trivial B-field, are classified by the K-theory of an infinite dimensional C*-algebra. In the case of B-fields whose curvature is pure torsion our description is shown to coincide with that of Witten.Peter Bouwknegt and Varghese Matha
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Operator algebra quantum homogeneous spaces of universal gauge groups
No full textIn this paper, we quantize universal gauge groups such as SU(∞), as well as their homogeneous spaces, in the σ-C*-algebra setting. More precisely, we propose concise definitions of σ-C*-quantum groups and σ-C*-quantum homogeneous spaces and explain these concepts here. At the same time, we put these definitions in the mathematical context of countably compactly generated spaces as well as C*-compact quantum groups and homogeneous spaces. We also study the representable K-theory of these spaces and compute these groups for the quantum homogeneous spaces associated to the quantum version of the universal gauge group SU(∞).Snigdhayan Mahanta, Varghese Matha
Cell wall degrading enzymes in barley
No full textMaria Hrmova, Andrew J. Harvey, Robert C. Lee, Mitali Banik, Jose N. Varghese and Geoffrey B. Finche
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