Skyrmions, Rational Maps & Scaling Identities

Starting from approximate Skyrmion solutions obtained using the rational map ansatz, improved approximate Skyrmions are constructed using scaling arguments. Although the energy improvement is small, the change of shape clarifies whether the true Skyrmions are more oblate or prolate.Comment: 13 pages, 3 figure

Hydrological Response of a Permeable Pavement Laboratory Rig for Stormwater Management.

Nowadays there is an increasing amount of everyday flood incidents around the world, the impact of which poses a challenge on the society, economy and environment. Under the Water Framework Directive (2000/60/EC), green infrastructure provided by sustainable drainage systems (SuDS) is the recommended policy to manage and treat storm water. This paper presents experimental work carried out in the laboratory on a permeable pavement rig, investigating mainly the short-term hydrology of the pavement, and the way that runoff percolates through the structure during simulated rainfall events. Results showed high flood mitigation capacity, encouraging further investigation of this type of SuDS

Weyl Equation and (Non)-Commutative SU(n+1) BPS Monopoles

We apply the ADHMN construction to obtain the SU(n+1)(for generic values of n) spherically symmetric BPS monopoles with minimal symmetry breaking. In particular, the problem simplifies by solving the Weyl equation, leading to a set of coupled equations, whose solutions are expressed in terms of the Whittaker functions. Next, this construction is generalized for non-commutative SU(n+1) BPS monopoles, where the corresponding solutions are given in terms of the Heun B functions.Comment: 16 pages, Latex. Few typos corrected, version to appear in JHE

Skyrmions and Bags in the 2D-O(3) model

Localized static solutions of the 2D-O(3) model are investigated in a representation with the 3-vector field $\vec Phi$ split into the unit vector $\hat Phi$ and the modulus $\Phi$. As in the nonlinear version of the model this allows for the definition of a topological winding number $B$, and for the separation of the complete configuration space into distinct $B$-sectors. For small values of the $\Phi^4$-coupling strength the stable energy minima in these sectors are characterized by bag formation in the modulus field which in the standard cartesian representation of the linear O(3) model would be unstable towards decay into the trivial B=0 vacuum. Stabilized by $B$-conservation they exhibit a surprising variety of very appealing features for multiply charged systems. With the total charge bound into one common deep bag opposite ways of distributing the topological charge density inside the bag can be realized: Pointlike structures which retain the individuality of single constituents (or doubly charged pairs), or a deconfined charge density spread uniformly throughout the interior of the bag. It is suggested that this extension supplies a crucial link to overcome the unsatisfactory existing mismatch between multiskyrmion configurations and nuclear structure.Comment: 13 pages, 15 figure

The nucleus as a fluid of skyrmions: Energy levels and nucleon properties in the medium

A model of a fluid of skyrmions coupled to a scalar and to the \o meson mean fields is developed. The central and spin-orbit potentials of a skyrmion generated by the fields predict correct energy levels in selected closed shell nuclei. The effect of the meson fields on the properties of skyrmions in nuclei is investigated.Comment: Latex format, 6 figures, Journal of Physics G, to be publishe

In Situ Characterization of Follicular Helper CD4 T Cells Using Multiplexed Imaging.

Follicular helper CD4 T (Tfh) cells play an essential role in the formation of germinal centers (GCs), where mature B cells proliferate, differentiate, and provide long-term protective humoral responses. Despite the extensive phenotypic characterization and identification of human Tfh cell subsets, their spatial positioning at tissue level is not well understood. Here, we describe a quantitative multiplexed immunofluorescence approach allowing for the comprehensive in situ characterization of Tfh cells in human tonsils and lymph nodes (LNs) from individuals with angioimmunoblastic T-cell lymphoma (AITL). We have developed eight multiplexed panels comprising a spectrum of Tfh cell markers, like PD-1, CXCR5, and ICOS, along with transcription factors (Bcl6, Tbet, GATA3), to assess their expression, frequencies, spatial distribution and co-localization in a quantitative manner. Combined analysis of relevant markers revealed the presence of several Tfh cell subsets at tissue level based on the differential expression of surface receptors, nuclear factors as well as their distinct localization within the follicular areas. Interestingly, we found a considerable amount of tonsillar Tfh cells expressing high levels of the Th2 regulator GATA3. The co-expression of GATA3, CXCR5, and BCL6, points to an important role of GATA3 for the generation of effector human Tfh cells. Furthermore, our data revealed significantly different Tfh cell profile signatures between health and disease. Therefore, our imaging platform generates meaningful information for the in situ characterization of human Tfh cells and could provide the base for future studies aiming to a comprehensive understanding of Tfh cell tissue heterogeneity

Non-BPS Dyons and Branes in the Dirac-Born-Infeld Theory

Non-BPS dyon solutions to D3-brane actions are constructed when one or more scalar fields describing transverse fluctuations of the brane, are considered. The picture emerging from such non-BPS configurations is analysed, in particular the response of the D-brane-string system to small perturbations.Comment: 16 pages, 4 figures, Revtex fil