Intersecting Dp-branes often give rise to chiral fermions living on their intersections. We study the construction of four-dimensional chiral gauge theories by considering configurations of type II D(3 + n)-branes wrapped on non-trivial n-cycles on T × (R/ZN), for n = 1, 2, 3. The gauge theories on the four non-compact dimensions of the brane world-volume are generically chiral and non-supersym...

We analyse a system of arbitrarily intersecting D–branes in ten– dimensional supergravity. Chiral anomalies are supported on the intersection branes, called I–branes. For non–transversal intersections anomaly cancellation has been realized until now only cohomologically but not locally, due to short–distance singularities. In this paper we present a consistent local cancellation mechanism, writ...

The shifted quantization condition of the M-theory 4-form G4 is well-known. The most naive generalization to type IIA string theory fails, an orientifold fourplane counterexample was found by Hori in hep-th/9805141. In this note we use D2-brane anomaly cancellation to find the corresponding shifted quantitization condition in IIA. Our analysis is consistent with the known O4-plane tensions if w...

We elucidate the structure of D terms in N = 1 orientifold compactifications with fluxes. As a case study, we consider a simple orbifold of the type-IIA theory with D6-branes at angles, O6-planes and general NSNS, RR and Scherk-Schwarz geometrical fluxes. We examine in detail the emergence of D terms, in their standard supergravity form, from an appropriate limit of the D-brane action. We deriv...

We review various K-theory classification conjectures in string theory. Sen conjecture based proposals classify D-brane trajectories in backgrounds with no H flux, while Freed-Witten anomaly based proposals classify conserved RR charges and magnetic RR fluxes in topologically time-independent backgrounds. In exactly solvable CFTs a classification of well-defined boundary states implies that the...

Influenza is one of the most important viral diseases that is common among the birds and the mammalsand is caused by specific viruses that belong to the Orthomyxoviridae family. Migratory aquatic birds arethe reservoir of the disease and there is a likelihood of the disease in any region. There are differentmethods for detecting the avian influenza, but by the point of detection rates, the ELIS...

  Background: Due to some limitations of serological methods in diagnosis of patients infected with HIV-1 (human immunodeficiency virus) and HCV (hepatitis C virus), it is profoundly important to use molecular methods for the detecting of these infectious agents. However, the most significant problems are the exorbitant cost of these methods and the need of a thermocycler which is an expensive...

Rapid prototyping has become an increasing part of product development process chains resulting in reduced time to market and reduced development costs. As manufacturers strive to further reduce development cycles to maintain market competitiveness, the use of reverse engineering technologies have started to play key roles in the product development cycles. Integration of these technologies int...

We investigate in the simplest compact D = 4 N = 1 Type IIB orientifold models the sigma-model symmetry suggested by the proposed duality of these models to heterotic orbifold vacua. This symmetry is known to be present at the classical level, and is associated to a composite connection involving untwisted moduli in the low-energy supergravity theory. In order to study possible anomalies arisin...