On the relation between the propagators of dual theories

In this paper, we show that the propagator of the dual of a general Proca-like theory, derived from the gauging iterative Noether Dualization Method, can be written by means of a simple relation between known propagators. This result is also a demonstration that the Lagrangian obtained by dualization describes the same physical particles as the ones present in the original theory at the expense of introducing new non-physical (ghosts) excitations.Comment: latex, 4 page

Generalized duality between local vector theories in D=2+1D=2+1

The existence of an interpolating master action does not guarantee the same spectrum for the interpolated dual theories. In the specific case of a generalized self-dual (GSD) model defined as the addition of the Maxwell term to the self-dual model in $D=2+1$, previous master actions have furnished a dual gauge theory which is either nonlocal or contains a ghost mode. Here we show that by reducing the Maxwell term to first order by means of an auxiliary field we are able to define a master action which interpolates between the GSD model and a couple of non-interacting Maxwell-Chern-Simons theories of opposite helicities. The presence of an auxiliary field explains the doubling of fields in the dual gauge theory. A generalized duality transformation is defined and both models can be interpreted as self-dual models. Furthermore, it is shown how to obtain the gauge invariant correlators of the non-interacting MCS theories from the correlators of the self-dual field in the GSD model and vice-versa. The derivation of the non-interacting MCS theories from the GSD model, as presented here, works in the opposite direction of the soldering approach.Comment: 11 pages, no figures, to appear in J. of High Energy Phy

Non-Chern-Simons Topological Mass Generation in (2+1) Dimensions

By dimensional reduction of a massive BF theory, a new topological field theory is constructed in (2+1) dimensions. Two different topological terms, one involving a scalar and a Kalb-Ramond fields and another one equivalent to the four-dimensional BF term, are present. We constructed two actions with these topological terms and show that a topological mass generation mechanism can be implemented. Using the non-Chern-Simons topological term, an action is proposed leading to a classical duality relation between Klein-Gordon and Maxwell actions. We also have shown that an action in (2+1) dimensions with the Kalb-Ramond field is related by Buscher's duality transformation to a massive gauge-invariant Stuckelberg-type theory.Comment: 8 pages, no figures, RevTE

Dual Linearised Gravity in Arbitrary Dimensions

We construct dual formulation of linearised gravity in first order tetrad formalism in arbitrary dimensions within the path integral framework following the standard duality algorithm making use of the global shift symmetry of the tetrad field. The dual partition function is in terms of the (mixed symmetric) tensor field $\Phi_{[\nu_{1}\nu_{2}...\nu_{d-3}]\nu}$ in {\it frame-like} formulation. We obtain in d-dimensions the dual Lagrangian in a closed form in terms of field strength of the dual frame-like field. Next by coupling a source with the (linear) Riemann tensor in d-dimensions, dual generating functional is obtained. Using this an operator mapping between (linear) Riemann tensor and Riemann tensor corresponding to the dual field is derived and we also discuss the exchange of equations of motion and Bianchi identity.Comment: 14 pages, typos corrected, Published version: Class. Quantum Grav. 22(2005)538

Higher Grading Conformal Affine Toda Teory and (Generalized) Sine-Gordon/Massive Thirring Duality

Some properties of the higher grading integrable generalizations of the conformal affine Toda systems are studied. The fields associated to the non-zero grade generators are Dirac spinors. The effective action is written in terms of the Wess-Zumino-Novikov-Witten (WZNW) action associated to an affine Lie algebra, and an off-critical theory is obtained as the result of the spontaneous breakdown of the conformal symmetry. Moreover, the off-critical theory presents a remarkable equivalence between the Noether and topological currents of the model. Related to the off-critical model we define a real and local Lagrangian provided some reality conditions are imposed on the fields of the model. This real action model is expected to describe the soliton sector of the original model, and turns out to be the master action from which we uncover the weak-strong phases described by (generalized) massive Thirring and sine-Gordon type models, respectively. The case of any (untwisted) affine Lie algebra furnished with the principal gradation is studied in some detail. The example of $\hat{sl}(n) (n=2,3)$ is presented explicitly.Comment: 28 pages, JHEP styl

Aligned multi-walled carbon nanotube-embodied hydrogel via low magnetic field: A strategy for engineering aligned injectable scaffolds

Injectable scaffolds are a promising strategy to restore and regenerate damaged and diseased tissues. They require minimally invasive procedure and allow the formation of an in-situ structure of any shape. However, the formation of 3D in-situ structure with aligned morphologies using a method which could be easily transferred to clinical settings remains a challenge. Herein, the rational design of an aligned injectable hydrogel-based scaffold via remote-induced alignment is reported. Carboxylated multi-walled carbon nanotubes (cMWCNT) are aligned into hydrogel via low magnetic field. The uniform dispersion and alignment of cMWCNT into the hydrogel are clearly demonstrated by small angle neutron scattering. The obtained aligned cMWCNT-embodied hydrogel is stable over 7 days at room temperature and as well at body temperature (i.e. 37 °C). As unique approach, the formation of MWCNT-hydrogel composite is investigated combining rheology with molecular dynamic and quantum mechanical calculations. The increase of MWCNT concentration into the hydrogel decreases the total energy promoting structural stabilization and increase of stiffness. The remote aligning of injectable hydrogel-based scaffold opens up horizons in the engineering of functional tissues which requires specific cell orientation.publishedVersio

Adolescent self-harm in Ghana: a qualitative interview-based study of first-hand accounts

Background: Recent prevalence studies suggest that self-harm among adolescents in sub-Saharan Africa is as common as it is in high income countries. However, very few qualitative studies exploring first-person accounts of adolescent self-harm are available from sub-Saharan Africa. We sought to explore the experiences and first-person perspectives of Ghanaian adolescents reporting self-harm - for deeper reflections on the interpretive repertoires available in their cultural context for making sense of self-harm in adolescents. Methods: Guided by a semi-structured interview protocol, we interviewed one-to-one 36 adolescents (24 in-school adolescents and 12 street-connected adolescents) on their experiences of self-harm. We applied experiential thematic analysis to the data. Results: Adolescents’ description of the background to their self-harm identified powerlessness in the family context and unwanted adultification in the family as key factors leading up to self-harm among both in-school and street-connected adolescents. Adolescents’ explanatory accounts identified the contradictory role of adultification as a protective factor against self-harm among street-connected adolescents. Self-harm among in-school adolescents was identified as a means of “enactment of tabooed emotions and contestations”, as a “selfish act and social injury”, as “religious transgression”, while it was also seen as improving social relations. Conclusions: The first-person accounts of adolescents in this study implicate familial relational problems and interpersonal difficulties as proximally leading to self-harm in adolescents. Self-harm in adolescents is interpreted as an understandable response, and as a strong communicative signal in response to powerlessness and family relationship difficulties. These findings need to be taken into consideration in the planning of services in Ghana and are likely to be generalisable to many other countries in sub-Saharan Africa