73 research outputs found
Supersymmetric Intersecting Branes on the Type IIA T^6/Z_4 orientifold
We study supersymmetric intersecting D6-branes wrapping 3-cycles in the Type
IIA T^6/Z_4 orientifold background. As a new feature, the 3-cycles in this
orbifold space arise both from the untwisted and the Z_2 twisted sectors. We
present an integral basis for the homology lattice, H_3(M,Z), in terms of
fractional 3-cycles, for which the intersection form involves the Cartan matrix
of E8. We show that these fractional D6-branes can be used to construct
supersymmetric brane configurations realizing a three generation Pati-Salam
model. Via brane recombination processes preserving supersymmetry, this GUT
model can be broken down to a standard-like model.Comment: 48 pages, TeX, harvmac, 8 figures, v4: some signs correcte
Orientifolds of K3 and Calabi-Yau Manifolds with Intersecting D-branes
We investigate orientifolds of type II string theory on K3 and Calabi-Yau
3-folds with intersecting D-branes wrapping special Lagrangian cycles. We
determine quite generically the chiral massless spectrum in terms of
topological invariants and discuss both orbifold examples and algebraic
realizations in detail. Intriguingly, the developed techniques provide an
elegant way to figure out the chiral sector of orientifold models without
computing any explicit string partition function. As a new example we derive a
non-supersymmetric Standard-like Model from an orientifold of type IIA on the
quintic Calabi-Yau 3-fold with wrapped D6-branes. In the case of supersymmetric
intersecting brane models on Calabi-Yau manifolds we discuss the D-term and
F-term potentials, the effective gauge couplings and the Green-Schwarz
mechanism. The mirror symmetric formulation of this construction is provided
within type IIB theory. We finally include a short discussion about the lift of
these models from type IIB on K3 to F-theory and from type IIA on Calabi-Yau
3-folds to M-theory on G_2 manifolds.Comment: 82 pages, harvmac, 5 figures. v2: references added. v3: T^6
orientifold corrected, JHEP versio
Progress in muscular dystrophy research with special emphasis on gene therapy
Duchenne muscular dystrophy (DMD) is an X-linked, progressive muscle-wasting disease caused by mutations in the DMD gene. Since the disease was described by physicians in the 19th century, information about the subject has been accumulated. One author (Sugita) was one of the coworkers who first reported that the serum creatine kinase (CK) level is elevated in progressive muscular dystrophy patients. Even 50 years after that first report, an elevated serum CK level is still the most useful marker in the diagnosis of DMD, a sensitive index of the state of skeletal muscle, and useful to evaluate therapeutic effects. In the latter half of this article, we describe recent progress in the therapy of DMD, with an emphasis on gene therapies, particularly exon skipping
Avaliação da qualidade de solos sob diferentes coberturas florestais e de pastagem no sul de Minas Gerais
Determinação do índice de qualidade subsuperficial em um Latossolo Amarelo Coeso dos Tabuleiros Costeiros, sob floresta natural
Propriedades químicas de um latossolo vermelho distrófico de cerrado sob diferentes usos e manejos
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