N=1 Super QCD and Fractional Branes

We show how to get the one-loop beta function and the chiral anomaly of N=1 Super QCD from a stack of fractional N D3-branes localized inside the world-volume of 2M fractional D7-branes on the orbifold C^3/(Z_2 x Z_2). They are obtained by analyzing the classical supergravity background generated by such a brane configuration, in the spirit of the gauge/gravity correspondence.Comment: 4 pages, LaTeX. Talk given at the IXth International Symposium on Particles, Strings and Cosmology PASCOS '03, Mumbai-India, January 3-8 2003. To appear in a special issue of Praman

epsilon'/epsilon in the Standard Model

In order to provide an estimate of eps'/eps several effective theories and physical effects have to be disentangled. In this talk I discuss how it is possible to predict eps '/eps taking into account all sources of large logs. The numerical result one obtains, \eps '/\eps \sim (1.7\pm 0.6) \cdot 10^{-4}, is in good agreement with present measurements.Comment: Talk presented at QCD2000, Montpellier july 200

New physics in \epsilon' from chromomagnetic contributions and limits on Left-Right symmetry

New physics in the chromomagnetic flavor changing transition s->dg* can avoid the strong GIM suppression of the Standard Model and lead to large contributions to CP-violating observables, in particular to the epsilon' parameter, that we address here. We discuss the case of the Left-Right symmetric models, where this contribution implies bounds on the phases of the right-handed quark mixing matrix, or in generic models with large phases a strong bound on the Left-Right symmetry scale. To the leading order, a numeric formula for epsilon' as a function of the short-distance coefficients for a wide class of models of new physics is given.Comment: 12 pages, Eq. 12 and related numerics amende

Hybrid conformal field theories

We describe a class of (2,2) superconformal field theories obtained by fibering a Landau-Ginzburg orbifold CFT over a compact Kaehler base manifold. While such models are naturally obtained as phases in a gauged linear sigma model, our construction is independent of such an embedding. We discuss the general properties of such theories and present a technique to study the massless spectrum of the associated heterotic compactification. We test the validity of our method by applying it to hybrid phases of linear models and comparing spectra among the phases

Learning from a well-documented geotechnical cold case : the Two Towers of Bologna, Italy.

The Garisenda Tower and the Asinelli Tower, also widely known as the Two Towers, are the best preserved and famous medieval towers in the city of Bologna (Northern Italy). Standing one close to the other, right in the heart of the city centre, the Two Towers are delicate remains of the old towered city, which counted more than 75 towers in the 12th century. The foundations of historic towers and the surrounding soil often hide major hazards for the long-term preservation of these heritage structures. The initial fundamental step to this aim is indeed a deep understanding of their original conception, foundations and subsoil. However, the idea that also such elements are an integral part of the overall structure, and thus subjected to the same conservation rules, is relatively new. The present paper outlines the investigation criteria applied to the soil-foundation systems of the Two Towers of Bologna and describes the authenticity of their characteristics, through the interpretation of new experimental data and the analysis of historical documents. A geotechnical perspective on this type of monuments turns out to be crucial in order to effectively understand the soil-structure interaction mechanisms, which govern their safety conditions over time. This study also aims to better understand the reasons why the Two Towers of Bologna, despite their numerous similarities, have reached completely different structural configurations. The methodology described to investigate this case study, which required the integration of several aspects, can be usefully applied to any historic tower

On the Gauge/Gravity Correspondence and the Open/Closed String Duality

In this article we review the conditions for the validity of the gauge/gravity correspondence in both supersymmetric and non-supersymmetric string models. We start by reminding what happens in type IIB theory on the orbifolds C^2/Z_2 and C^3/(Z_2 x Z_2), where this correspondence beautifully works. In these cases, by performing a complete stringy calculation of the interaction among D3 branes, it has been shown that the fact that this correspondence works is a consequence of the open/closed duality and of the absence of threshold corrections. Then we review the construction of type 0 theories with their orbifolds and orientifolds having spectra free from both open and closed string tachyons and for such models we study the validity of the gauge/gravity correspondence, concluding that this is not a peculiarity of supersymmetric theories, but it may work also for non-supersymmetric models. Also in these cases, when it works, it is again a consequence of the open/closed string duality and of vanishing threshold corrections.Comment: Invited review article for Int. J. Mod. Phys. A, 95 pages, 2 figures, 3 tables, LaTeX. References and acknowledgements adde

EXOSOMES SIGNALLING IN HUMAN GLIOMA STEM CELLS: THE CENTRAL ROLE OF V-ATPASE PROTON PUMP ACTIVITY

Recent evidences highlighted that glioblastomas (GBM) secreted microvesicles (EVs), particularly exosomes (Exo) and large oncosomes (LO), play a major role in the cross-talk between tumor cell and non-neoplastic parenchyma. Recent work from our group has identified the vacuolar pump H+-ATPase (V-ATPase) as an important effector of GBM growth and glioma stem cells (GSC) maintenance. Additionally, in ExoCarta database V-ATPase subunits have been described in Exo from different cancer cell types. Taken together, these data identify V-ATPase as an important driver of gliomagenesis, and a novel, actionable therapeutic target for disease intervention. However, the role of V-ATPase in reprogramming the GBM microenvironment has not been previously investigated. The aim of this project was investigate production, biological effect and content of extracellular vesicles according to proton pump activity in glioma stem cells. Our data show that GSC are able to produce different types of EVs, which are internalized by recipient cells of different histology, such as non-neoplastic brain tumor margins, primary GBM monolayers (both differentiated and undifferentiated), and commercial glioma cultures. Exo and LO from GSC induces in recipient cells distinct effects. In particular, Exo significantly increased cell growth and cell motility, and these effects were stronger with Exo produced by NS with higher V-ATPase expression (V1G1HIGH NS). On the other hand, LO were able to strongly induce the sphere formation ability of primary GBM cultures. This effect lasted up 90 days after co-culture. In both situations, the block of V-ATPase activity by Bafilomycin A1 in NS-producing EVs completely reverted the effects. Interestingly, exosomes are able to vehiculate on their surface the V-ATPase G1 subunit, and its protein level increased in recipient cells after co-culture with EVs. At the molecular level, profiling of Exo-derived miRNAs distinguishes V1G1HIGH NS from V1G1LOW cultures. In silico analysis and annotation of miRNA target genes showed an enrichment of cancer, cell cycle and MAPK/Erk pathways. Regarding signaling pathway modulation by Exo in recipient cells, exosomes from V1G1HIGH NS activated the MAPK/Erk pathway. Altogether, these data point toward the central role of different EV types in GBM communication and suggest a role of the V-ATPase proton pump in regulating exosomes contents

Linear pose estimate from corresponding conics

We propose here a new method to recover the orientation and position of a plane by matching at least three projections of a conic lying on the plane itself. The procedure is based on rearranging the conic projection equations such that the non linear terms are eliminated. It works with any kind of conic and does not require that the shape of the conic is known a-priori. The method was extensively tested using ellipses, but it can also be used for hyperbolas and parabolas. It was further applied to pairs of lines, which can be viewed as a degenerate case of hyperbola, without requiring the correspondence problem to be solved first. Critical configurations and numerical stability have been analyzed through simulations. The accuracy of the proposed algorithm was compared to that of traditional algorithms and of a trinocular vision system using a set of landmarks

Exact N=2 Supergravity Solutions With Polarized Branes

We construct several classes of exact supersymmetric supergravity solutions describing D4 branes polarized into NS5 branes and F-strings polarized into D2 branes. These setups belong to the same universality class as the perturbative solutions used by Polchinski and Strassler to describe the string dual of N=1* theories. The D4-NS5 setup can be interpreted as a string dual to a confining 4+1 dimensional theory with 8 supercharges, whose properties we discuss. By T-duality, our solutions give Type IIB supersymmetric backgrounds with polarized branes.Comment: 22 pages. v2 - references added, details clarifie