17 research outputs found
Torus knots and mirror symmetry
We propose a spectral curve describing torus knots and links in the B-model.
In particular, the application of the topological recursion to this curve
generates all their colored HOMFLY invariants. The curve is obtained by
exploiting the full Sl(2, Z) symmetry of the spectral curve of the resolved
conifold, and should be regarded as the mirror of the topological D-brane
associated to torus knots in the large N Gopakumar-Vafa duality. Moreover, we
derive the curve as the large N limit of the matrix model computing torus knot
invariants.Comment: 30 pages + appendix, 3 figure
(Unoriented) T-folds with few T's
We use the combined action of Z_2-chiral reflections (T-dualities) and shifts
to build N=1,2 supersymmetric four-dimensional string compactifications with
few moduli. In particular, we consider Z_2^4 asymmetric orbifolds of Type IIB
on the maximal torus of SO(12) that mimic N=2 Calabi-Yau compactifications with
small "effective" Hodge numbers starting from (h_{11}, h_{21})=(1,1). We
analyze possible unoriented projections, providing Type I examples with or
without open strings. N=1 oriented asymmetric shift-orbifolds of Type IIB with
few chiral multiplets are also presented.Comment: 26 pages, minor corrections, references adde
Superconformal Selfdual Sigma-Models
A range of bosonic models can be expressed as (sometimes generalized)
-models, with equations of motion coming from a selfduality constraint.
We show that in D=2, this is easily extended to supersymmetric cases, in a
superspace approach. In particular, we find that the configurations of fields
of a superconformal coset models which satisfy some
selfduality constraint are automatically solutions to the equations of motion
of the model. Finally, we show that symmetric space -models can be seen
as infinite-dimensional \tfG/\tfH models constrained by a selfduality
equation, with \tfG the loop extension of and \tfH a maximal
subgroup. It ensures that these models have a hidden global \tfG symmetry
together with a local \tfH gauge symmetry.Comment: 21 pages; v2 few corrections and references added; v3 exposition
change
Hidden Symmetries and Dirac Fermions
In this paper, two things are done. First, we analyze the compatibility of
Dirac fermions with the hidden duality symmetries which appear in the toroidal
compactification of gravitational theories down to three spacetime dimensions.
We show that the Pauli couplings to the p-forms can be adjusted, for all simple
(split) groups, so that the fermions transform in a representation of the
maximal compact subgroup of the duality group G in three dimensions. Second, we
investigate how the Dirac fermions fit in the conjectured hidden overextended
symmetry G++. We show compatibility with this symmetry up to the same level as
in the pure bosonic case. We also investigate the BKL behaviour of the
Einstein-Dirac-p-form systems and provide a group theoretical interpretation of
the Belinskii-Khalatnikov result that the Dirac field removes chaos.Comment: 30 page
Long-Term Alterations of Cytokines and Growth Factors Expression in Irradiated Tissues and Relation with Histological Severity Scoring
PURPOSE: Beside its efficacy in cancer treatment, radiotherapy induces degeneration of healthy tissues within the irradiated area. The aim of this study was to analyze the variations of proinflammatory (IL-1α, IL-2, IL-6, TNF-α, IFN-γ), profibrotic (TGF-β1), proangiogneic (VEGF) and stem cell mobilizing (GM-CSF) cytokines and growth factors in an animal model of radiation-induced tissue degeneration. MATERIALS AND METHODS: 24 rats were irradiated unilaterally on the hindlimb at a monodose of 30 Gy. Six weeks (n=8), 6 months (n=8) and 1 year (n=8) after irradiation the mediators expression in skin and muscle were analyzed using Western blot and the Bio-Plex® protein array (BPA) technology. Additional histological severity for fibrosis, inflammation, vascularity and cellularity alterations scoring was defined from histology and immnunohistochemistry analyses. RESULTS: A significant increase of histological severity scoring was found in irradiated tissue. Skin tissues were more radio-sensitive than muscle. A high level of TGF-β1 expression was found throughout the study and a significant relation was evidenced between TGF-β1 expression and fibrosis scoring. Irradiated tissue showed a chronic inflammation (IL-2 and TNF-α significantly increased). Moreover a persistent expression of GM-CSF and VEGF was found in all irradiated tissues. The vascular score was related to TGF-β1 expression and the cellular alterations score was significantly related with the level of IL-2, VEGF and GM-CSF. CONCLUSION: The results achieved in the present study underline the complexity and multiplicity of radio-induced alterations of cytokine network. It offers many perspectives of development, for the comprehension of the mechanisms of late injuries or for the histological and molecular evaluation of the mode of action and the efficacy of rehabilitation techniques
Exact solution of Chern-Simons-matter matrix models with characteristic/orthogonal polynomials
Heterotic T-folds with a small number of neutral moduli
We discuss non-geometric supersymmetric heterotic string models in D=4, in
the framework of the free fermionic construction. We perform a systematic scan
of models with four a priori left-right asymmetric Z_2 projections and shifts.
We analyze some 2^{20} models, identifying 18 inequivalent classes and
addressing variants generated by discrete torsions. They do not contain
geometrical or trivial neutral moduli, apart from the dilaton. However, we show
the existence of flat directions in the form of exactly marginal deformations
and identify patterns of symmetry breaking where product gauge groups, realized
at level one, are broken to their diagonal at higher level. We also describe an
"inverse Gepner map" from Heterotic to Type II models that could be used, in
certain non geometric settings, to define "effective" topological invariants.Comment: 37 page
Stroma-rich co-culture multicellular tumor spheroids as a tool for photoactive drugs screening
Conventional 3D multicellular tumor spheroids of head and neck squamous cell carcinoma (HNSCC) consisting exclusively of cancer cells have some limitations. They are compact cell aggregates that do not interact with their extracellular milieu, thus su_ering from both insu_cient extracellular matrix (ECM) deposition and absence of di_erent types of stromal cells. In order to better mimic in vivo HNSCC tumor microenvironment, we have constructed a 3D stroma-rich in vitro model of HNSCC, using cancer-associated MeWo skin fibroblasts and FaDu pharynx squamous cell carcinoma. The expression of stromal components in heterospheroids was confirmed by immunochemical staining. The generated co-culture FaDu/MeWo spheroids were applied to study penetration, distribution and antitumor e_cacy of photoactive drugs such as Temoporfin and Chlorin e6 used in the photodynamic therapy flow cytometry and fluorescence microscopy techniques. We also investigated the distribution of photodiagnostic agent Indocyanine Green. We demonstrated that the presence of stroma influences the behavior of photoactive drugs in di_erent ways: (i) No e_ect on Indocyanine Green distribution; (ii) lower accumulation of Chlorin e6; (iii) better penetration and PDT e_ciency of Temoporfin. Overall, the developed stroma-rich spheroids enlarge the arsenal of in vitro pre-clinical models forhigh-throughput screening of anti-cancer drugs