Gauge invariance, background fields and modified Ward identities

In this talk the gauge symmetry for Wilsonian flows in pure Yang-Mills theories is discussed. The background field formalism is used for the construction of a gauge invariant effective action. The symmetries of the effective action under gauge transformations for both the gauge field and the auxiliary background field are separately evaluated. Modified Ward-Takahashi and background field identities are used in my study. Finally it is shown how the symmetry properties of the full theory are restored in the limit where the cut-off is removed.Comment: 6 pages, to appear in the Proceedings of the 2nd Conference on the Exact Renormalization Group, Rome 200

A call for collaboration: perception of religious and spiritual leaders on mental health (a Portuguese sample)

To assess the relationship and collaborations between mental health professionals and religious and spiritual leaders, eleven representatives of ten different religious affiliations in Portugal participated in this qualitative study. Major findings reported showed that religious leaders perceive themselves as important agents in promoting and preserving their congregants’ mental health, as well as aiding their recovery processes; however this occurs without much referral to or collaboration with mental health professionals. These findings are discussed, as well as why and how a healthy collaboration between mental health professionals and religious leaders can positively impact the psychotherapeutic relationship and clinical outcomes with religious/spiritual clients.info:eu-repo/semantics/acceptedVersio

Exfoliation microcracks in building granite. Implications for anisotropy

Granite is found in many world heritage monuments and cities. It continues to be one of the most widely used stones in today's construction, given its abundance, uniformity and durability. Quarrymen traditionally cut this rock along its orthogonal slip planes, where splitting is easier. Ranked by ease of splitting, these planes are rift, grain and hardway. Granite is traditionally quarried along the rift plane where coplanar exfoliation microcracks coalesce developing a flat surface. This splitting surface minimizes the cost and effort of subsequent hewing. Rift plane was predominantly used on the fair face of ashlars in heritage buildings worldwide. Determining the petrographic and petrophysical behaviour of these three orthogonal splitting planes in granite is instrumental to understanding decay in ashlars and sculptures. The decay of building granite is different in each splitting plane. Alpedrete granite was the stone selected for this study based on the orientation and distribution of exfoliation microcracks and the characterisation of their implications for the anisotropy of petrophysical properties such as ultrasonic wave propagation, capillarity, air permeability, micro-roughness and surface hardness. Inter- and intracrystalline microcrack length and spacing were also measured and quantified. The findings show that the splitting planes in Alpedrete granite are determined by the orientation of exfoliation microcracks, which as a rule are generally straight and intracrystalline and determine the anisotropy of the petrophysical properties analysed. Splitting planes are the orientation that should be applied when performing laboratory tests for the petrographic and petrophysical properties of building granite.This study was funded by the Regional Government of Madrid, Spain, in the framework of the GEOMATERIALS-2CM [S2013/MIT-2914] programme.Peer reviewe

Thermal stress-induced microcracking in building granite

Microcracking induced by wide fluctuations in temperature affects granite quality and durability, making the stone more vulnerable to decay. Determining the extent of that effect is not always straightforward, however, given the excellent durability of these materials. Four types of construction granite quarried in the region of Madrid, Spain, and frequently used in both the built heritage and in de novo construction (Alpedrete, Cadalso de los Vidrios, Colmenar Viejo and Zarzalejo) were exposed to 42 thermal cycles (105–20 °C; UNE-EN, 14066, 2003). Petrographic and petrophysical properties were analysed using both destructive and non-destructive techniques. Microcracking generated in the granite stones by 42 thermal cycles had barely any impact on their petrophysical properties, which are the parameters normally assessed to establish material quality and durability. Their petrographic properties, which are not generally assessed in this type of studies, were affected, however. This study contends that petrographic analysis is needed to objectively quantify the actual quality and durability of the most highly resistant materials when petrophysical studies are inconclusive. Petrographic and fluorescence microscopy, along with fractography, are among the most prominent techniques for petrographic exploration. Thanks to the deployment of these techniques, mineral microcracking could be monitored throughout the present tests conducted. The microscopic findings revealed substantial micro-textural and microstructural change in and around the granite minerals, which play a prominent role in decay. The findings showed that pre-existing microcracks coalesced and generated further microcracking as decay progressed. Microcracking was most intense in Zarzalejo granite due to its textural characteristics determined by its high feldspar content. Microscopic observation revealed that the microstructure of feldspar minerals, with their crystallographic anisotropies and secondary mineral phases, favoured microcrack development. Zarzalejo granite exhibited lower quality and durability than Colmenar Viejo and Cadalso de los Vidrios granites, which were more resistant to heat treatment.This study was funded by the project GEOMATERIALES 2 (S2013/MIT-2914).Peer reviewe

Causes of scaling on bush-hammered heritage ashlars: a case study—Plaza Mayor of Madrid (Spain)

Masons have traditionally used granite anisotropy to cut and lay the stone. Scaling, a common type of granite decay, is observed worldwide. This study explored the relationship between weathering and cut planes in heritage ashlars, specifically in the stone on Madrid’s Plaza Mayor, whose construction dates back to 1590. The 71 rectangular granite columns that support its porticoes are oriented towards the four cardinal points. All 71 have one exposed side that faces the square, one protected side facing inward and two semi-protected sides perpendicular to the other two. The sides of the columns are also oriented to the points of the compass. This study aimed to identify the prevailing orientation of scaling, if any, in the granite ashlars and to determine how this process is affected by climate, microclimate (orientation), use, hewing and exfoliation microcracks. All four sides of the 71 columns were mapped (284 in all) to analyse scaling height, distribution and orientation. The findings showed that the microcracks are vertically oriented and decline in density and length with depth from the surface. Scaling was observed on the lower ashlars in the columns to a maximum depth of 3 mm. Determining the direction of exfoliation microcracks is imperative to understanding decay mechanisms in granite ashlars and sculptures and that information must be taken into consideration when applying conservation treatments.This study was funded by the Community of Madrid under the GEOMATERIALS (S2009/MAT-1629) and GEOMATERIALS-2CM (S2013/MIT-2914) research programmes and Project 921349 awarded to the Complutense University of Madrid’s Research Group ‘Alteración y Conservación de los Materiales Pétreos del Patrimonio’Peer reviewe

Confining potential in a color dielectric medium with parallel domain walls

We study quark confinement in a system of two parallel domain walls interpolating different color dielectric media. We use the phenomenological approach in which the confinement of quarks appears considering the QCD vacuum as a color dielectric medium. We explore this phenomenon in QCD_2, where the confinement of the color flux between the domain walls manifests, in a scenario where two 0-branes (representing external quark and antiquark) are connected by a QCD string. We obtain solutions of the equations of motion via first-order differential equations. We find a new color confining potential that increases monotonically with the distance between the domain walls.Comment: RevTex4, 5 pages, 1 figure; version to appear in Int. J. Mod. Phys.

The Specific Heat of a Ferromagnetic Film.

We analyze the specific heat for the $O(N)$ vector model on a $d$-dimensional film geometry of thickness $L$ using ``environmentally friendly'' renormalization. We consider periodic, Dirichlet and antiperiodic boundary conditions, deriving expressions for the specific heat and an effective specific heat exponent, \alpha\ef. In the case of $d=3$, for $N=1$, by matching to the exact exponent of the two dimensional Ising model we capture the crossover for \xi_L\ra\infty between power law behaviour in the limit {L\over\xi_L}\ra\infty and logarithmic behaviour in the limit {L\over\xi_L}\ra0 for fixed $L$, where $\xi_L$ is the correlation length in the transverse dimensions.Comment: 21 pages of Plain TeX. Postscript figures available upon request from [email protected]

Towards a new theory of practice for community health psychology

The article sets out the value of theorizing collective action from a social science perspective that engages with the messy actuality of practice. It argues that community health psychology relies on an abstract version of Paulo Freire’s earlier writing, the Pedagogy of the Oppressed, which provides scholar-activists with a ‘map’ approach to collective action. The article revisits Freire’s later work, the Pedagogy of Hope, and argues for the importance of developing a ‘journey’ approach to collective action. Theories of practice are discussed for their value in theorizing such journeys, and in bringing maps (intentions) and journeys (actuality) closer together