Half-BPS quotients in M-theory: ADE with a twist

We classify Freund-Rubin backgrounds of eleven-dimensional supergravity of the form AdS_4 x X^7 which are at least half BPS; equivalently, smooth quotients of the round 7-sphere by finite subgroups of SO(8) which admit an (N>3)-dimensional subspace of Killing spinors. The classification is given in terms of pairs consisting of an ADE subgroup of SU(2) and an automorphism defining its embedding in SO(8). In particular we find novel half-BPS quotients associated with the subgroups of type D_n (for n>5), E_7 and E_8 and their outer automorphisms.Comment: 16 pages; V2: notational inconsistencies addressed, final version to be published in JHE

Supersymmetry and homogeneity of M-theory backgrounds

We describe the construction of a Lie superalgebra associated to an arbitrary supersymmetric M-theory background, and discuss some examples. We prove that for backgrounds with more than 24 supercharges, the bosonic subalgebra acts locally transitively. In particular, we prove that backgrounds with more than 24 supersymmetries are necessarily (locally) homogeneous.Comment: 19 pages (Erroneous Section 6.3 removed from the paper.

The holonomy of IIB supercovariant connection

We show that the holonomy of the supercovariant connection of IIB supergravity is contained in SL(32, \bR). We also find that the holonomy reduces to a subgroup of SL(32-N)\st (\oplus^N \bR^{32-N}) for IIB supergravity backgrounds with $N$ Killing spinors. We give the necessary and sufficient conditions for a IIB background to admit $N$ Killing spinors. A IIB supersymmetric probe configuration can involve up to 31 linearly independent planar branes and preserves one supersymmetry.Comment: 8 pages, latex. v2: Minor correction

Invariant Killing spinors in 11D and type II supergravities

We present all isotropy groups and associated $\Sigma$ groups, up to discrete identifications of the component connected to the identity, of spinors of eleven-dimensional and type II supergravities. The $\Sigma$ groups are products of a Spin group and an R-symmetry group of a suitable lower dimensional supergravity theory. Using the case of SU(4)-invariant spinors as a paradigm, we demonstrate that the $\Sigma$ groups, and so the R-symmetry groups of lower-dimensional supergravity theories arising from compactifications, have disconnected components. These lead to discrete symmetry groups reminiscent of R-parity. We examine the role of disconnected components of the $\Sigma$ groups in the choice of Killing spinor representatives and in the context of compactifications.Comment: 22 pages, typos correcte

On the maximal superalgebras of supersymmetric backgrounds

In this note we give a precise definition of the notion of a maximal superalgebra of certain types of supersymmetric supergravity backgrounds, including the Freund-Rubin backgrounds, and propose a geometric construction extending the well-known construction of its Killing superalgebra. We determine the structure of maximal Lie superalgebras and show that there is a finite number of isomorphism classes, all related via contractions from an orthosymplectic Lie superalgebra. We use the structure theory to show that maximally supersymmetric waves do not possess such a maximal superalgebra, but that the maximally supersymmetric Freund-Rubin backgrounds do. We perform the explicit geometric construction of the maximal superalgebra of AdS_4 x S^7 and find that is isomorphic to osp(1|32). We propose an algebraic construction of the maximal superalgebra of any background asymptotic to AdS_4 x S^7 and we test this proposal by computing the maximal superalgebra of the M2-brane in its two maximally supersymmetric limits, finding agreement.Comment: 17 page

Co-expression networks in generation of induced pluripotent stem cells.

We developed an adenoviral vector, in which Yamanaka's four reprogramming factors (RFs) were controlled by individual CMV promoters in a single cassette (Ad-SOcMK). This permitted coordinated expression of RFs (SOX2, OCT3/4, c-MYC and KLF4) in a cell for a transient period of time, synchronizing the reprogramming process with the majority of transduced cells assuming induced pluripotent stem cell (iPSC)-like characteristics as early as three days post-transduction. These reprogrammed cells resembled human embryonic stem cells (ESCs) with regard to morphology, biomarker expression, and could be differentiated into cells of the germ layers in vitro and in vivo. These iPSC-like cells, however, failed to expand into larger iPSC colonies. The short and synchronized reprogramming process allowed us to study global transcription changes within short time intervals. Weighted gene co-expression network analysis (WGCNA) identified sixteen large gene co-expression modules, each including members of gene ontology categories involved in cell differentiation and development. In particular, the brown module contained a significant number of ESC marker genes, whereas the turquoise module contained cell-cycle-related genes that were downregulated in contrast to upregulation in human ESCs. Strong coordinated expression of all four RFs via adenoviral transduction may constrain stochastic processes and lead to silencing of genes important for cellular proliferation

ARTE ACCIONAL DURACIONAL, TRASFORMACIONES DEL CUERPO ATEMPORALES

El pasado y el presente del arte muestran evidencias de los artistas avocados a una transformaci\uf3n del cuerpo humano a trav\ue9s de distintas ideas que integran elementos artificiales. El uso de implantes, clonaciones del cuerpo y redistribuci\uf3n del g\ue9nero proyectan cada vez m\ue1s una transgresi\uf3n a la sociedad hasta cuestionarla y educarla. El cuerpo se convierte en la imagen, en el reflejo de aquello que somos y no somos, es as\ued Sterlac, Orlan y Argelia Bravo transitan el mundo cognoscible de otra manera implantando conceptos desde el \ue1mbito art\uedstico que transforman el futuro m\ue1s all\ue1 de la humanidad misma, lo transhumano. El arte accional nos trae del pasado a personajes como Sterlac, quien en las intervenciones de su propio cuerpo con incisiones e implantes que oyen sus ideas, su tercera oreja en el brazo son ejemplos, de una necesidad de cambios. Por otra parte quiz\ue1s con una influencia del feminismo y cr\uedtica social, Orlan deja de ser ella y se transforma en todas las mujeres en una que son objeto de deseo y admiraci\uf3n, cercanas a lo sublime que propone Kant, vende sus objeto de las performances desde las salas de intervenciones quir\ufargicas al mundo mientras ella eterniza sus implantes. En Venezuela Argelia Bravo, aprovecha ese espacio inter sexo, o transhumano, m\ue1s all\ue1 de la convenci\uf3n biol\uf3gica, propuso impresiones rosas sobre lienzo de un cuerpo diferente, de un cuerpo femenino superior y masculino inferior, refiri\ue9ndose al mismo cuerpo y sus miembros fision\uf3micos. Tres artistas que presentan la convenci\uf3n otra, de existencia de un cuerpo, de muchos cuerpos, del ente m\ue1s all\ue1 de lo humano. Palabas Claves del Autor: arte, transhumano, posthumano, cuerpo. ABSTRACT The past and the present of art show evidence of the avocados artists to a transformation of the human body through different ideas that integrate artificial elements. The use of implants, body cloning and gender redistribution increasingly project a transgression to society until questioning and educating it. The body becomes the image, in the reflection of what we are and are not, so Sterlac, Orlan and Algeria Bravo transpose the knowable world in another way implanting concepts from the artistic realm that transform the future beyond humanity itself , The transhuman. The action art brings us from the past to characters like Sterlac, who in the interventions of his own body with incisions and implants that hear his ideas, his third ear in the arm are examples of a need for change. On the other hand, perhaps with an influence of feminism and social criticism, Orlan ceases to be her and transforms herself into all the women in one who are objects of desire and admiration, close to the sublime that Kant proposes, sells his object of the performances since The surgical intervention rooms to the world while she perpetuates her implants. In Venezuela Algeria Bravo, she takes advantage of this space between sex, or transhuman, beyond the biological convention, proposed pink prints on canvas of a different body, of an upper and lower masculine body, referring to the same body and its physiognomic members. Three artists who present the other convention, of existence of a body, of many bodies, of the being beyond the human Keywords: Art, transhuman, posthuman, body<br