Marginal Deformations of Field Theories with AdS_4 Duals

We generate new AdS_4 solutions of D=11 supergravity starting from AdS_4 x X_7 solutions where X_7 has U(1)^3 isometry. We consider examples where X_7 is weak G_2, Sasaki-Einstein or tri-Sasakian, corresponding to d=3 SCFTs with N=1,2 or 3 supersymmetry, respectively, and where the deformed solutions preserve N=1,2 or 1 supersymmetry, respectively. For the special cases when X_7 is M(3,2), Q(1,1,1) or N(1,1)_I we identify the exactly marginal deformation in the dual field theory. We also show that the volume of supersymmetric 5-cycles of N(1,1)_I agrees with the conformal dimension predicted by the baryons of the dual field theory.Comment: 28 pages, 2 figures; v2. typos correcte

Bulk vs. Boundary Dynamics in Anti-de Sitter Spacetime

We investigate the details of the bulk-boundary correspondence in Lorentzian signature anti-de Sitter space. Operators in the boundary theory couple to sources identified with the boundary values of non-normalizable bulk modes. Such modes do not fluctuate and provide classical backgrounds on which bulk excitations propagate. Normalizable modes in the bulk arise as a set of saddlepoints of the action for a fixed boundary condition. They fluctuate and describe the Hilbert space of physical states. We provide an explicit, complete set of both types of modes for free scalar fields in global and Poincar\'e coordinates. For \ads{3}, the normalizable and non-normalizable modes originate in the possible representations of the isometry group \SL_L\times\SL_R for a field of given mass. We discuss the group properties of mode solutions in both global and Poincar\'e coordinates and their relation to different expansions of operators on the cylinder and on the plane. Finally, we discuss the extent to which the boundary theory is a useful description of the bulk spacetime.Comment: Standard LaTeX, 28 pages, 2 postscript figures. v2: References added. Substantial revision in section 3 of treatment of global modes; non-normalizable modes have arbitrary time dependence. Revised discussion of low-mass modes and puzzle raised re: coupling of the dual boundary operators. v3: unwanted paragraph removed. v4: Sec. 5.2 correcte

Vacuum interpolation in supergravity via super p-branes

We show that many of the recently proposed supersymmetric p-brane solutions of d=10 and d=11 supergravity have the property that they interpolate between Minkowski spacetime and a compactified spacetime, both being supersymmetric supergravity vacua. Our results imply that the effective worldvolume action for small fluctuations of the super p-brane is a supersingleton field theory for $(adS)_{p+2}$, as has been often conjectured in the past.Comment: 8p

Spectrum of Chiral Operators in Strongly Coupled Gauge Theories

We analyze the large $N$ spectrum of chiral primary operators of three dimensional fixed points of the renormalization group. Using the space-time picture of the fixed points and the correspondence between anti-de Sitter compactifications and conformal field theories we are able to extract the dimensions of operators in short superconformal multiplets. We write down some of these operators in terms of short distance theories flowing to these non-trivial fixed points in the infrared.Comment: harvmac, 16 pages, one acknowledgement adde

Measuring text simplification with the crowd

Text can often be complex and difficult to read, especially for peo ple with cognitive impairments or low literacy skills. Text simplifi cation is a process that reduces the complexity of both wording and structure in a sentence, while retaining its meaning. However, this is currently a challenging task for machines, and thus, providing effective on-demand text simplification to those who need it re mains an unsolved problem. Even evaluating the simplicity of text remains a challenging problem for both computers, which cannot understand the meaning of text, and humans, who often struggle to agree on what constitutes a good simplification. This paper focuses on the evaluation of English text simplifica tion using the crowd. We show that leveraging crowds can result in a collective decision that is accurate and converges to a consen sus rating. Our results from 2,500 crowd annotations show that the crowd can effectively rate levels of simplicity. This may allow sim plification systems and system builders to get better feedback about how well content is being simplified, as compared to standard mea sures which classify content into ‘simplified ’ or ‘not simplified’ categories. Our study provides evidence that the crowd could be used to evaluate English text simplification, as well as to create simplified text in future work

Supermembranes and Super Matrix Models

We review recent developments in the theory of supermembranes and their relation to matrix models.Comment: Invited lecture presented at the Corfu Workshop, September 20 - 26, 1998, of the TMR Project "Quantum Aspects of Gauge Theories, Supersymmetry and Unification" (ERBFMRXCT96-0045), to appear in the proceedings. Latex 41 p

Neuroinflammation, Mast Cells, and Glia: Dangerous Liaisons

The perspective of neuroinflammation as an epiphenomenon following neuron damage is being replaced by the awareness of glia and their importance in neural functions and disorders. Systemic inflammation generates signals that communicate with the brain and leads to changes in metabolism and behavior, with microglia assuming a pro-inflammatory phenotype. Identification of potential peripheral-to-central cellular links is thus a critical step in designing effective therapeutics. Mast cells may fulfill such a role. These resident immune cells are found close to and within peripheral nerves and in brain parenchyma/meninges, where they exercise a key role in orchestrating the inflammatory process from initiation through chronic activation. Mast cells and glia engage in crosstalk that contributes to accelerate disease progression; such interactions become exaggerated with aging and increased cell sensitivity to stress. Emerging evidence for oligodendrocytes, independent of myelin and support of axonal integrity, points to their having strong immune functions, innate immune receptor expression, and production/response to chemokines and cytokines that modulate immune responses in the central nervous system while engaging in crosstalk with microglia and astrocytes. In this review, we summarize the findings related to our understanding of the biology and cellular signaling mechanisms of neuroinflammation, with emphasis on mast cell-glia interactions

Giant Gravitons on AdS_4 x CP^3 and their Holographic Three-point Functions

We find a simple parametrization of the anti-symmetric giant graviton in AdS_4 x CP^3, first constructed in arXiv:1108.3084 [hep-th], dual to the anti-symmetric Schur polynomial involving two bi-fundamental complex scalar fields of ABJM theory. Using this parametrization we evaluate in a semi-classical approach the three-point function of two such giant gravitons and one point-like graviton considering both extremal and non-extremal configurations. We likewise discuss the case of the symmetric giant graviton in AdS_4 x CP^3. Finally, we provide an expression for the planar three-point function of chiral primary operators in ABJM at strong coupling and find that the results for the giant graviton three-point functions reduce to this expression in the point-like limit.Comment: 1+16 pages. v2 added a referenc

Melatonin Promotes Oligodendroglial Maturation of Injured White Matter in Neonatal Rats

OBJECTIVE:To investigate the effects of melatonin treatment in a rat model of white matter damage (WMD) in the developing brain. Additionally, we aim to delineate the cellular mechanisms of melatonin effect on the oligodendroglial cell lineage. METHODS:A unilateral ligation of the uterine artery in pregnant rat at the embryonic day 17 induces fetal hypoxia and subsequent growth restriction (GR) in neonatal pups. GR and control pups received a daily intra-peritoneal injection of melatonin from birth to post-natal day (P) 3. RESULTS:Melatonin administration was associated with a dramatic decrease in microglial activation and astroglial reaction compared to untreated GR pups. At P14, melatonin prevented white matter myelination defects with an increased number of mature oligodendrocytes (APC-immunoreactive) in treated GR pups. Conversely, melatonin was not found to be associated with an increased density of total oligodendrocytes (Olig2-immunoreactive), suggesting that melatonin is able to promote oligodendrocyte maturation but not proliferation. These effects appear to be melatonin-receptor dependent and were reproduced in vitro. INTERPRETATION:These data suggest that melatonin has a strong protective effect on developing damaged white matter through decreased microglial activation and oligodendroglial maturation leading to a normalization of the myelination process. Consequently, melatonin should be a considered as an effective neuroprotective candidate not only in perinatal brain damage but also in inflammatory and demyelinating diseases observed in adults

Cloud computing and RESERVOIR project

The support for complex services delivery is becoming a key point in current internet technology. Current trends in internet applications are characterized by on demand delivery of ever growing amounts of content. The future internet of services will have to deliver content intensive applications to users with quality of service and security guarantees. This paper describes the RESERVOIR project and the challenge of a reliable and effective delivery of services as utilities in a commercial scenario. It starts by analyzing the needs of a future infrastructure provider and introducing the key concept of a service oriented architecture that combines virtualisation-aware grid with grid-aware virtualisation, while being driven by business service management. This article will then focus on the benefits and the innovations derived from the RESERVOIR approach. Eventually, a high level view of RESERVOIR general architecture is illustrated