113 research outputs found
Neuroimmunology - the past, present and future
Neuroimmunology as a separate discipline has its roots in the fields of neurology, neuroscience and immunology. Early studies of the brain by Golgi and Cajal, the detailed clinical and neuropathology studies of Charcot and Thompsonâs seminal paper on graft acceptance in the central nervous system, kindled a now rapidly expanding research area, with the aim of understanding pathological mechanisms of inflammatory components of neurological disorders. While neuroimmunologists originally focused on classical neuroinflammatory disorders, such as multiple sclerosis and infections, there is strong evidence to suggest that the immune response contributes to genetic white matter disorders, epilepsy, neurodegenerative diseases, neuropsychiatric disorders, peripheral nervous system and neuroâoncological conditions, as well as ageing. Technological advances have greatly aided our knowledge of how the immune system influences the nervous system during development and ageing, and how such responses contribute to disease as well as regeneration and repair. Here, we highlight historical aspects and milestones in the field of neuroimmunology and discuss the paradigm shifts that have helped provide novel insights into disease mechanisms. We propose future perspectives including molecular biological studies and experimental models that may have the potential to push many areas of neuroimmunology. Such an understanding of neuroimmunology will open up new avenues for therapeutic approaches to manipulate neuroinflammation
On unitary subsectors of polycritical gravities
We study higher-derivative gravity theories in arbitrary space-time dimension
d with a cosmological constant at their maximally critical points where the
masses of all linearized perturbations vanish. These theories have been
conjectured to be dual to logarithmic conformal field theories in the
(d-1)-dimensional boundary of an AdS solution. We determine the structure of
the linearized perturbations and their boundary fall-off behaviour. The
linearized modes exhibit the expected Jordan block structure and their inner
products are shown to be those of a non-unitary theory. We demonstrate the
existence of consistent unitary truncations of the polycritical gravity theory
at the linearized level for odd rank.Comment: 22 pages. Added references, rephrased introduction slightly.
Published versio
Nonlinear Dynamics of Parity-Even Tricritical Gravity in Three and Four Dimensions
Recently proposed "multicritical" higher-derivative gravities in Anti de
Sitter space carry logarithmic representations of the Anti de Sitter isometry
group. While generically non-unitary already at the quadratic, free-theory
level, in special cases these theories admit a unitary subspace. The simplest
example of such behavior is "tricritical" gravity. In this paper, we extend the
study of parity-even tricritical gravity in d = 3, 4 to the first nonlinear
order. We show that the would-be unitary subspace suffers from a linearization
instability and is absent in the full non-linear theory.Comment: 22 pages; v2: references added, published versio
Tricritical gravity waves in the four-dimensional generalized massive gravity
We construct a generalized massive gravity by combining quadratic curvature
gravity with the Chern-Simons term in four dimensions. This may be a candidate
for the parity-odd tricritical gravity theory. Considering the AdS vacuum
solution, we derive the linearized Einstein equation, which is not similar to
that of the three dimensional (3D) generalized massive gravity. When a
perturbed metric tensor is chosen to be the Kerr-Schild form, the linearized
equation reduces to a single massive scalar equation. At the tricritical points
where two masses are equal to -1 and 2, we obtain a log-square wave solution to
the massive scalar equation. This is compared to the 3D tricritical generalized
massive gravity whose dual is a rank-3 logarithmic conformal field theory.Comment: 17 pages, 1 figure, version to appear in EPJ
Holographic two-point functions for 4d log-gravity
We compute holographic one- and two-point functions of critical
higher-curvature gravity in four dimensions. The two most important operators
are the stress tensor and its logarithmic partner, sourced by ordinary massless
and by logarithmic non-normalisable gravitons, respectively. In addition, the
logarithmic gravitons source two ordinary operators, one with spin-one and one
with spin-zero. The one-point function of the stress tensor vanishes for all
Einstein solutions, but has a non-zero contribution from logarithmic gravitons.
The two-point functions of all operators match the expectations from a
three-dimensional logarithmic conformal field theory.Comment: 35 pages; v2: typos corrected, added reference; v3: shorter
introduction, minor changes in the text in section 3, added reference;
published versio
Duality Symmetries and G^{+++} Theories
We show that the non-linear realisations of all the very extended algebras
G^{+++}, except the B and C series which we do not consider, contain fields
corresponding to all possible duality symmetries of the on-shell degrees of
freedom of these theories. This result also holds for G_2^{+++} and we argue
that the non-linear realisation of this algebra accounts precisely for the form
fields present in the corresponding supersymmetric theory. We also find a
simple necessary condition for the roots to belong to a G^{+++} algebra.Comment: 35 pages. v2: 2 appendices added, other minor corrections. v3: tables
corrected, other minor changes, one appendix added, refs. added. Version
published in Class. Quant. Gra
Finite and infinite-dimensional symmetries of pure N=2 supergravity in D=4
We study the symmetries of pure N=2 supergravity in D=4. As is known, this
theory reduced on one Killing vector is characterised by a non-linearly
realised symmetry SU(2,1) which is a non-split real form of SL(3,C). We
consider the BPS brane solutions of the theory preserving half of the
supersymmetry and the action of SU(2,1) on them. Furthermore we provide
evidence that the theory exhibits an underlying algebraic structure described
by the Lorentzian Kac-Moody group SU(2,1)^{+++}. This evidence arises both from
the correspondence between the bosonic space-time fields of N=2 supergravity in
D=4 and a one-parameter sigma-model based on the hyperbolic group SU(2,1)^{++},
as well as from the fact that the structure of BPS brane solutions is neatly
encoded in SU(2,1)^{+++}. As a nice by-product of our analysis, we obtain a
regular embedding of the Kac-Moody algebra su(2,1)^{+++} in e_{11} based on
brane physics.Comment: 70 pages, final version published in JHE
E10 and Gauged Maximal Supergravity
We compare the dynamics of maximal three-dimensional gauged supergravity in
appropriate truncations with the equations of motion that follow from a
one-dimensional E10/K(E10) coset model at the first few levels. The constant
embedding tensor, which describes gauge deformations and also constitutes an
M-theoretic degree of freedom beyond eleven-dimensional supergravity, arises
naturally as an integration constant of the geodesic model. In a detailed
analysis, we find complete agreement at the lowest levels. At higher levels
there appear mismatches, as in previous studies. We discuss the origin of these
mismatches.Comment: 34 pages. v2: added references and typos corrected. Published versio
Euclid Preparation. XXVIII. Forecasts for ten different higher-order weak lensing statistics
Recent cosmic shear studies have shown that higher-order statistics (HOS) developed by independent teams now outperform standard two-point estimators in terms of statistical precision thanks to their sensitivity to the non-Gaussian features of large-scale structure. The aim of the Higher-Order Weak Lensing Statistics (HOWLS) project is to assess, compare, and combine the constraining power of ten different HOS on a common set of -like mocks, derived from N-body simulations. In this first paper of the HOWLS series, we computed the nontomographic (, ) Fisher information for the one-point probability distribution function, peak counts, Minkowski functionals, Betti numbers, persistent homology Betti numbers and heatmap, and scattering transform coefficients, and we compare them to the shear and convergence two-point correlation functions in the absence of any systematic bias. We also include forecasts for three implementations of higher-order moments, but these cannot be robustly interpreted as the Gaussian likelihood assumption breaks down for these statistics. Taken individually, we find that each HOS outperforms the two-point statistics by a factor of around two in the precision of the forecasts with some variations across statistics and cosmological parameters. When combining all the HOS, this increases to a times improvement, highlighting the immense potential of HOS for cosmic shear cosmological analyses with . The data used in this analysis are publicly released with the paper
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