Ehrenfest relations at the glass transition: solution to an old paradox

In order to find out whether there exists a thermodynamic description of the glass phase, the Ehrenfest relations along the glass transition line are reconsidered. It is explained that the one involving the compressibility is always satisfied, and that the one involving the specific heat is principally incorrect. Thermodynamical relations are presented for non-ergodic systems with a one-level tree in phase space. They are derived for a spin glass model, checked for other models, and expected to apply, e.g., to glass forming liquids. The second Ehrenfest relation gets a contribution from the configurational entropy.Comment: 4 pages revtex, to appear in Phys. Rev. Let

"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

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

Visual and personalized quality of life assessment app for people with severe mental health problems:Qualitative evaluation

Background:  QoL-ME is a digital visual personalized quality of life assessment app for people with severe mental health problems. Research reveals that e-mental health apps frequently suffer from low engagement and fall short of expectations regarding their impact on patients' daily lives. Studies often indicate that e-mental health apps ought to respect the needs and preferences of end users to achieve optimal user engagement. Objective:  The aim of this study was to explore the experiences of users regarding the usability and functionality of QoL-ME and whether the app is actionable and beneficial for patients. Methods:  End users (n=8) of QoL-ME contributed to semistructured interviews. An interview guide was used to direct the interviews. All interviews were audiorecorded and transcribed verbatim. Transcriptions were analyzed and coded thematically. Results:  Analysis revealed 3 main themes: (1) benefit, (2) actionability, and (3) characteristics of the QoL-ME. The first theme reveals that the QoL-ME app was beneficial for the majority of respondents, primarily by prompting them to reflect on their quality of life. The current version is not yet actionable; the actionability of the QoL-ME app may be improved by enabling users to view their scores over time and by supplying practical advice for quality of life improvements. Overall, participants had positive experiences with the usability, design, and content of the app. Conclusions:  The QoL-ME app can be beneficial to users as it provides them with insight into their quality of life and elicits reflection. Incorporating more functionalities that facilitate self-management, such as advice and strategies for improving areas that are lacking, will likely make the app actionable. Patients positively regarded the usability, design, and contents of the QoL-ME app

Green function Retrieval and Time-reversal in a Disordered World

We apply the theory of multiple wave scattering to two contemporary, related topics: imaging with diffuse correlations and stability of time-reversal of diffuse waves, using equipartition, coherent backscattering and frequency speckles as fundamental concepts.Comment: 1 figur

Comparing Aimed Movements in the Real World and in Virtual Reality

The study of aimed movements has a long history, starting at least as far back as 1899 when Woodworth proposed a two-component model in which aimed movements are broken into an initial ballistic phase and an additional control phase. In this paper, we use Woodworth’s model for experimentally comparing aimed movements in the real world with those in a virtual environment. Trajectories from real world movements have been collected and compared to trajectories of movements taken from a virtual environment. From this, we show that significant temporal differences arise in both the ballistic and control phases, but the difference is much larger in the control phase; users’ improvement is relatively greater in the virtual world than in the real world. They progress more in ballistic phase in the real world, but more in correction phase in the virtual world. These results allow us to better understand the pointing tasks in virtual environments

Comparing Aimed Movements in the Real World and in Virtual Reality

The study of aimed movements has a long history, starting at least as far back as 1899 when Woodworth proposed a two-component model in which aimed movements are broken into an initial ballistic phase and an additional control phase. In this paper, we use Woodworth’s model for experimentally comparing aimed movements in the real world with those in a virtual environment. Trajectories from real world movements have been collected and compared to trajectories of movements taken from a virtual environment. From this, we show that significant temporal differences arise in both the ballistic and control phases, but the difference is much larger in the control phase; users’ improvement is relatively greater in the virtual world than in the real world. They progress more in ballistic phase in the real world, but more in correction phase in the virtual world. These results allow us to better understand the pointing tasks in virtual environments

The induced action of W3 gravity

The induced action of W_3 gravity Schoutens, C.J.M.; Ooguri, H.; Sevrin, A.; van Nieuwenhuizen, P. Published in: Communications in Mathematical Physics DOI: 10.1007/BF02099396 Link to publication Citation for published version (APA): Schoutens, K., Ooguri, H., Sevrin, A., & van Nieuwenhuizen, P. (1992). The induced action of W_3 gravity. Communications in Mathematical Physics, 145, 515-539. https://doi.org/10.1007/BF02099396 General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 01 Jul 2019 Commun. Math. Phys. 145, 515-539 (1992) Abstract. We obtain the induced action F [h, b] for chiral W3 gravity in the c~ ___ limit from the induced action of a gauged Sl(3, R) Wess-Zumino-Witten model by imposing constraints on the currents of the latter. In the process we find a closed gauge algebra for the gauge sector of W3 gravity in which the currents T and W become auxiliary fields. An explicit realization of T and W in terms of the gauge fields is given. In terms of new fields r and s, which are a generalization of Polyakov's f variable for ordinary gravity, the complete induced action l-'[h, b; c~ _ 0o] becomes local