Supersymmetric observables of N=1 Quantum Field Theories on a twisted S^1 x S^3

Recent years have seen a big progress in the understanding of quantum field theories defined in curved backgrounds. In particular, in the presence of supersymmetry it has been possible to derive many exact results for large classes of background manifolds. The thesis will consider a simple N=1 quantum field theory defined on a manifold diffeomorphic to S^1 x S^3, review some known results derived through the technique of dimensional reduction, and extend them to the more general case where the 3-sphere is twisted over the circle. A reformulation of the results in terms of Hopf surfaces and their complex structure parameters will be discussed. This background plays an important role in holography as it corresponds to the boundary of supersymmetric black holes in five-dimensional Anti de Sitter space, with the twisting of the sphere corresponding to rotation parameters.ope

Chern-Simons theory and its applications

The aim of this thesis is to introduce and study basic general properties and certain mathematical and physical aspects of Chern-Simons field theories, as well as their application to the description of particles with fractional statistics and spin on the plane called anyons.ope

Matrix models from black hole geometries

Supersymmetric, magnetically charged (and possibly accelerating) black holes in AdS4 that uplift on Sasaki-Einstein manifolds Y7 to M-theory have a dual matrix model description. The matrix model in turn arises by localization of the 3d $\mathcal{N}$ = 2 SCFTs, dual to the AdS4 vacuum, on the black hole horizon geometry, which is a Riemann surface Σg (or a spindle Σ). We identify the imaginary part t of the continuously distributed eigenvalues in the matrix model, and their density function ρ(t), with natural geometric quantities associated with the M-theory circle action U(1)M on the near-horizon geometry AdS2 × Y9, the internal space Y9 being a Y7 fibration over Σg (or Σ). Moreover, we argue that the points where ρ′(t) is discontinuous match with the classical action of BPS probe M2-branes wrapping AdS2 and the M-theory circle. We illustrate our findings with the ABJM and ADHM theories, whose duals have Y7 = S7/ℤk, and some of their flavoured variants corresponding to other toric Y7

Entropy functions for accelerating black holes

We introduce an entropy function for supersymmetric accelerating black holes in $AdS_4$, that uplift on general Sasaki-Einstein manifolds $X_7$ to solutions of M-theory. This allows one to compute the black hole entropy without knowing the explicit solutions. A dual holographic microstate counting would follow from computing certain supersymmetric partition functions of Chern-Simons-matter theories compactified on a spindle. We make a general prediction for a class of such partition functions in terms of ``blocks'', with each block being constructed from the partition function on a three-sphere.Comment: 6 page

Gravitational Blocks, Spindles and GK Geometry

We derive a gravitational block formula for the supersymmetric action for a general class of supersymmetric AdS solutions, described by GK geometry. Extremal points of this action describe supersymmetric AdS$_3$ solutions of type IIB supergravity, sourced by D3-branes, and supersymmetric AdS$_2$ solutions of $D=11$ supergravity, sourced by M2-branes. In both cases, the branes are also wrapped over a two-dimensional orbifold known as a spindle, or a two-sphere. We develop various geometric methods for computing the gravitational block contributions, allowing us to recover previously known results for various explicit supergravity solutions, and to significantly generalize these results to other compactifications. For the AdS$_3$ solutions we give a general proof that our off-shell supersymmetric action agrees with an appropriate off-shell $c$-function in the dual field theory, establishing a very general exact result in holography. For the AdS$_2$ solutions our gravitational block formula allows us to obtain the entropy for supersymmetric, magnetically charged and accelerating black holes in AdS$_4$.Comment: 106 pages, 2 figure

Mesenchymal Stem Cell Treatment Perspectives in Peripheral Nerve Regeneration: Systematic Review

Traumatic peripheral nerve lesions affect hundreds of thousands of patients every year; their consequences are life-altering and often devastating and cause alterations in movement and sensitivity. Spontaneous peripheral nerve recovery is often inadequate. In this context, nowadays, cell therapy represents one of the most innovative approaches in the field of nerve repair therapies. The purpose of this systematic review is to discuss the features of different types of mesenchymal stem cells (MSCs) relevant for peripheral nerve regeneration after nerve injury. The published literature was reviewed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A combination of the keywords “nerve regeneration”, “stem cells”, “peripheral nerve injury”, “rat”, and “human” were used. Additionally, a “MeSH” research was performed in PubMed using the terms “stem cells” and “nerve regeneration”. The characteristics of the most widely used MSCs, their paracrine potential, targeted stimulation, and differentiation potentials into Schwann-like and neuronal-like cells are described in this paper. Considering their ability to support and stimulate axonal growth, their remarkable paracrine activity, their presumed differentiation potential, their extremely low immunogenicity, and their high survival rate after transplantation, ADSCs appear to be the most suitable and promising MSCs for the recovery of peripheral nerve lesion. Clinical considerations are finally reported

Stem Cell-Derived Human Striatal Progenitors Innervate Striatal Targets and Alleviate Sensorimotor Deficit in a Rat Model of Huntington Disease

Huntington disease (HD) is an inherited late-onset neurological disorder characterized by progressive neuronal loss and disruption of cortical and basal ganglia circuits. Cell replacement using human embryonic stem cells may offer the opportunity to repair the damaged circuits and significantly ameliorate disease conditions. Here, we showed that in-vitro-differentiated human striatal progenitors undergo maturation and integrate into host circuits upon intra-striatal transplantation in a rat model of HD. By combining graft-specific immunohistochemistry, rabies virus-mediated synaptic tracing, and ex vivo electrophysiology, we showed that grafts can extend projections to the appropriate target structures, including the globus pallidus, the subthalamic nucleus, and the substantia nigra, and receive synaptic contact from both host and graft cells with 6.6 ± 1.6 inputs cell per transplanted neuron. We have also shown that transplants elicited a significant improvement in sensory-motor tasks up to 2 months post-transplant further supporting the therapeutic potential of this approach

Motor neuron degeneration, severe myopathy and TDP-43 increase in a transgenic pig model of SOD1-linked familiar ALS

Amyotrophic Lateral Sclerosis (ALS) is a neural disorder gradually leading to paralysis of the whole body. Alterations in superoxide dismutase SOD1 gene have been linked with several variants of familial ALS. Here, we investigated a transgenic (Tg) cloned swine model expressing the human pathological hSOD1G93A allele. As in patients, these Tg pigs transmitted the disease to the progeny with an autosomal dominant trait and showed ALS onset from about 27 months of age. Post mortem analysis revealed motor neuron (MN) degeneration, gliosis and hSOD1 protein aggregates in brainstem and spinal cord. Severe skeletal muscle pathology including necrosis and inflammation was observed at the end stage, as well. Remarkably, as in human patients, these Tg pigs showed a quite long presymptomatic phase in which gradually increasing amounts of TDP-43 were detected in peripheral blood mononuclear cells. Thus, this transgenic swine model opens the unique opportunity to investigate ALS biomarkers even before disease onset other than testing novel drugs and possible medical devices