Rafael Mas Hernández

The SU(3) spin chain sigma model and string theory

The ferromagnetic integrable SU(3) spin chain provides the one loop anomalous dimension of single trace operators involving the three complex scalars of N = 4 supersymmetric Yang-Mills. We construct the non-linear sigma model describing the continuum limit of the SU(3) spin chain. We find that this sigma model corresponds to a string moving with large angular momentum in the five-sphere in AdS5 × S 5 . The energy and spectrum of fluctuations for rotating circular strings with angular momenta along three orthogonal directions of the five-sphere is reproduced as a particular case from the spin chain sigma model.

Glueball masses for the deformed conifold theory

We obtain the spectrum of glueball masses for the N = 1 non-conformal cascade theory whose supergravity dual was recently constructed by Klebanov and Strassler. The glueball masses are calculated by solving the supergravity equations of motion for the dilaton and the two-form in the deformed conifold background.

Spin chain sigma models with fermions

The complete one-loop planar dilatation operator of N = 4 supersymmetric Yang-Mills is isomorphic to the hamiltonian of an integrable PSU(2 , 2|4) quantum spin chain. We construct the non-linear sigma models describing the continuum limit of the SU(1|3) and SU(2|3) sectors of the complete N = 4 chain. We explicitely identify the spin chain sigma model with the one for a superstring moving in AdS 5 × S 5 with large angular momentum along the five-sphere.

Branes wrapped on coassociative cycles

Abstract We obtain a supergravity solution arising when D6-branes are wrapped on coassociative four-cycles of constant curvature in seven manifolds of G 2 holonomy. The solutions preserve two supercharges and thus represent supergravity duals of three-dimensional Yang–Mills with N =1 supersymmetry. When uplifted to eleven dimensions our solution describes M-theory on the background of an eight manifold with spin(7) holonomy.

Albinism and agenesis of the corpus callosum with profound developmental delay : Vici syndrome, evidence for autosomal recessive inheritance

We report on two sibs and two other unrelated patients with agenesis of corpus callosum, oculocutaneous albinism, repeated infections, and cardiomyopathy. All manifested postnatal growth retardation, microcephaly, and profound developmental delay. Additional central nervous system anomalies present in at least one patient included hypoplasia of the cerebellar vermis, white matter neuronal heterotopia, or bilateral schizencephaly. Repeated viral, bacterial, and fungal infections were consistent with a primary immunodeficiency. However, immunological studies showed variable, nonspecific findings. Cardiomyopathy with progressive heart failure or infection led to death before age 2 years in three of the patients. This syndrome was first described by Vici et al. [1988: Am. J. Med. Genet. 29:1-8]. The four patients reported herein confirm this unique disorder. Affected sibs of both sexes born to unaffected parents provide evidence for autosomal recessive inheritance.

An Eight-dimensional approach to G2 manifolds

Abstract We develop a systematic approach to G 2 holonomy manifolds with an SU (2)× SU (2) isometry using maximal eight-dimensional gauged supergravity to describe D6-branes wrapped on deformed three-spheres. A quite general metric ansatz that generalizes the celebrated Bryant–Salamon metric involves nine functions. We show that only six of them are the independent ones and derive the general first order system of differential equations that they obey. As a byproduct of our analysis, we generalize the notion of the twist that relates the spin and gauge connections in a way that involves non-trivially the scalar fields.

Quantum deformed magnon kinematics

The dispersion relation for planar = 4 supersymmetric Yang-Mills is identified with the Casimir of a quantum deformed two-dimensional kinematical symmetry, Eq(1, 1). The quantum deformed symmetry algebra is generated by the momentum, energy and boost, with deformation parameter q = e2πi/λ. Representing the boost as the infinitesimal generator for translations on the rapidity space leads to an elliptic uniformization with crossing transformations implemented through translations by the elliptic half-periods. This quantum deformed algebra can be interpreted as the kinematical symmetry of a discrete integrable model with lattice spacing given by the BMN length a = 2π/(λ)1/2. The interpretation of the boost generator as the corner transfer matrix is briefly discussed.The dispersion relation for planar = 4 supersymmetric Yang-Mills is identified with the Casimir of a quantum deformed two-dimensional kinematical symmetry, Eq(1, 1). The quantum deformed symmetry algebra is generated by the momentum, energy and boost, with deformation parameter q = e2?i/?. Representing the boost as the infinitesimal generator for translations on the rapidity space leads to an elliptic uniformization with crossing transformations implemented through translations by the elliptic half-periods. This quantum deformed algebra can be interpreted as the kinematical symmetry of a discrete integrable model with lattice spacing given by the BMN length a = 2?/(?)1/2. The interpretation of the boost generator as the corner transfer matrix is briefly discussed.

Elliptic solutions in the Neumann-Rosochatius system with mixed flux

Closed strings spinning in AdS_3 x S^3 x T^4 with mixed Ramond-Ramond and Neveu-Schwarz-NeveuSchwarz three-form fluxes are described by a deformation of the one-dimensional Neumann-Rosochatius integrable system. In this articlewe find general solutions to this systemthat can be expressed in terms of elliptic functions. We consider closed strings rotating either in S^3 with two different angularmomenta or in AdS_3 with one spin. To find the solutions, we will need to extend the Uhlenbeck integrals of motion of the Neumann-Rosochatius system to include the contribution from the flux. In the limit of pure Neveu-Schwarz-NeveuSchwarz flux, where the problem can be described by a supersymmetricWess-Zumino-Witten model, we find exact expressions for the classical energy in terms of the spin and the angular momenta of the spinning string.

Branes with fluxes wrapped on spheres

Following an eight-dimensional gauged supergravity approach we construct the most general solution describing D6-branes wrapped on a Kahler four-cycle taken to be the product of two spheres of different radii. Our solution interpolates between a Calabi–Yau four-fold and the spaces S^(2) × S^(2) × S^(2) × IR^(2) or S^(2) × S^(2) × IR^(4) , depending on generic choices for the parameters. Then we turn on a background four-form field strength, corresponding to D2-branes, and show explicitly how our solution is deformed. For a particular choice of parameters it represents a flow from a Calabi–Yau four-fold times the three-dimensional Minkowski space-time in the ultraviolet, to the space-time AdS_(4) × Q^(1,1,1) in the infrared. In general, the solution in the infrared has a singularity which within type-IIA supergravity corresponds to the near horizon geometry of the solution for the D2-D6 system. Finally, we uncover the relation with work done in the eighties on Freund–Rubin type compactifications.

Hydranencephaly after Maternal Butane‐gas Intoxication during Pregnancy

A newborn infant who suffered intra‐uterine anoxia is described, whose mother inhaled butane gas accidentally during the sixth month of pregnancy. The infant was born at 39 weeks. Ultrasonography and neuroradiological studies (CT scan and angiography) showed an almost complete absence of both cerebral hemispheres. The thalamus, brainstem and cerebellum were preserved. These findings were compatible with hydranencephaly. The authors believe that the malformation was due to intra‐uterine anoxia occurring during fetal brain‐development.