Consistent boundary conditions for supergravity

We derive the complete orbit of boundary conditions for supergravity models which is closed under the action of all local symmetries of these models, and which eliminates spurious field equations on the boundary. We show that the Gibbons-Hawking boundary conditions break local supersymmetry if one imposes local boundary conditions on all fields. Nonlocal boundary conditions are not ruled out. We extend our analysis to BRST symmetry and to the Hamiltonian formulation of these models.Comment: 37 pages, v2: references added, v3: misprint correcte

Ginzburg-Landau theory of the cluster glass phase

On the basis of a recent field theory for site-disordered spin glasses a Ginzburg-Landau free energy is proposed to describe the low temperatures glassy phase(s) of site-disordered magnets. The prefactors of the cubic and dominant quartic terms change gradually along the transition line in the concentration-temperature phase diagram. Either of them may vanish at certain points $(c_*, T_*)$, where new transition lines originate. The new phases are classifiedComment: 6 pages Revtex, 5 figures. To appear in J. Phys. A. Let

A landscape of non-supersymmetric AdS vacua on coset manifolds

We construct new families of non-supersymmetric sourceless type IIA AdS4 vacua on those coset manifolds that also admit supersymmetric solutions. We investigate the spectrum of left-invariant modes and find that most, but not all, of the vacua are stable under these fluctuations. Generically, there are also no massless moduli.Comment: 20 pages, 11 figures, v2: added some clarifications, references, v3: corrections addressing comments refere

Role of Visual Dysfunction in Postural Control in Children With Cerebral Palsy

Introduction: Deficient postural control is one of the key problems in cerebral palsy (CP). Little, however, is known about the specific nature of postural problems of children with CP, nor of the relation between abnormal posture and dysfunction of the visual system. Aim of the study: To provide additional information on the association of abnormalities in postural control and visual dysfunction of the anterior or posterior part of the visual system. Methods: Data resulting from ophthalmologic, orthoptic, neurological, neuro-radiological, and ethological investigations of more than 313 neurologically impaired children were retrospectively analyzed. Results: Abnormal postural control related to ocular and ocular motor disorders consisted of anomalous head control and subsequent abnormal head posture and torticollis. The abnormal postural control related to retrochiasmatical damage of the visual system consisted of a torticollis combined with adjustment of the upper part of the body, as if at the same time adapting to a combination of defects and optimizing residual visual functions. Conclusion: Visual dysfunctions play a distinct role in the postural control of children with CP

Self-Dual Conformal Supergravity and the Hamiltonian Formulation

In terms of Dirac matrices the self-dual and anti-self-dual decomposition of a conformal supergravity is given and a self-dual conformal supergravity theory is developed as a connection dynamic theory in which the basic dynamic variabes include the self-dual spin connection i.e. the Ashtekar connection rather than the triad. The Hamiltonian formulation and the constraints are obtained by using the Dirac-Bergmann algorithm. PACS numbers: 04.20.Cv, 04.20.Fy,04.65.+

Boundary Terms in Supergravity and Supersymmetry

We begin with the simplest possible introduction to supergravity. Then we discuss its spin 3/2 stress tensor; these results are new. Next, we discuss boundary conditions on fields and boundary actions for N=1 supergravity. Finally, we discuss new boundary contributions to the mass and central charge of monopoles in N=4 super Yang-Mills theory. All models are in 3+1 dimensions.Comment: 15 pages. Talk given by P. van Nieuwenhuizen at the Einstein-celebration gravitational conference at Puri (India) in December 200

"Optical conductance fluctuations: diagrammatic analysis in Landauer approach and non-universal effects"

The optical conductance of a multiple scattering medium is the total transmitted light of a diffuse incoming beam. This quantity, very analogous to the electronic conductance, exhibits universal conductance fluctuations. We perform a detailed diagrammatic analysis of these fluctuations. With a Kadanoff-Baym technique all the leading diagrams are systematically generated. A cancellation of the short distance divergencies occurs, that yields a well behaved theory. The analytical form of the fluctuations is calculated and applied to optical systems. Absorption and internal reflections reduce the fluctuations significantly.Comment: 25 pages Revtex 3.0, 18 seperate postscript figure

Quality of life of people with severe mental health problems:Testing an interactive model

Improvement of subjective quality of life (QoL) is seen as an important treatment outcome in clinical practice. The aim of this study is to test the theoretical model of Cummins, which includes a homeostatic management system. According to this model, objective variables are almost irrelevant to general well-being, while the feeling of having an influence on one’s circumstances (perceived deficit) is related to subjective QoL. The variables of the Cummins model were operationalised based on the Lancashire Quality of Life Profile, a structured interview to assess the subjective QoL of people with severe mental health problems. The Cummins model was tested using structural equation modelling and a mediator model between Objective QoL, Subjective QoL and Perceived Deficit. Subjective QoL and General Well-Being were significantly related and having a meaningful perspective in life was related to General Well-Being. Contrary to the Cummins model, both Objective QoL and Perceived Deficit had a significant relation to Subjective QoL and Perceived Deficit was a partial mediator between Objective QoL and Subjective QoL. Cummins’ theoretical model was partially confirmed. The current study suggests that meaningful (treatment) evaluation of subjective QoL can only be performed if objective QoL, General Well-Being and subjective evaluation (Perceived Deficit and Framework) are taken into account

Worth a thousand words?:Visual concept mapping of the quality of life of people with severe mental health problems

Objectives: Conventional approaches to quality of life (QoL) measurement rely heavily on verbal, language-based communication. They require respondents to have significant cognitive and verbal ability, making them potentially unsuitable for people with severe mental health problems. To facilitate an alternative approach to QoL assessment, the current study aims to develop an alternative, visual representation of QoL for people with severe mental health problems. Methods: An alternative, visual adaptation of the concept mapping method was used to construct this visual representation of QoL. Eighty-two participants (i.e., patients, care professionals, and family members) contributed to this study. Results were processed statistically to construct the concept map. Results: The concept map contains 160 unique visual statements, grouped into 8 clusters labelled (1) Support and Attention, (2) Social Contacts, (3) Happiness and Love, (4) Relaxation and Harmony, (5) Leisure, (6) Lifestyle, (7) Finances, and (8) Health and Living. Examples of visual statements are pictures of family silhouettes, romantic couples, natural scenes, houses, sports activities, wallets and coins, smiley faces, and heart shapes. The clusters were interpreted and labelled by participants. Conclusions: Almost all of the statements correspond to clusters found in previous (non-visual) QoL research. Hence, QoL domains can also be presented visually

On a possible new R^2 theory of supergravity

We consider a new MacDowell-Mansouri R^2-type of supergravity theory, an extension of conformal supergravity, based on the superalgebra Osp(1|8). Invariance under local symmetries with negative Weyl weight is achieved by imposing chirality-duality and double-duality constraints on curvatures, along with the usual constraint of vanishing supertorsion. An analysis of the remaining gauge symmetries shows that those with vanishing Weyl weight are invariances of the action at the linearized level. For the symmetries with positive Weyl weight we find that invariance of the action would require further modifications of the transformation rules. This conclusion is supported by a kinematical analysis of the closure of the gauge algebra.Comment: 52 pages, Late