Potential energy landscape of finite-size mean-field models for glasses

connected spin-glass models with a discontinuous transition. In the thermodynamic limit the equilibrium properties in the high temperature phase are described by the schematic Mode Coupling Theory of super-cooled liquids. We show that {\it finite-size} fully connected spin-glass models do exhibit properties typical of Lennard-Jones systems when both are near the critical glass transition, where thermodynamics is ruled by energy minima distribution. Our study opens the way to consider activated processes in real glasses through finite-size corrections (i.e. calculations beyond the saddle point approximation) in mean-field spin-glass models.Comment: 8 pages, 3 postscript figures, EPL format, improved versio

Coarsening of Disordered Quantum Rotors under a Bias Voltage

We solve the dynamics of an ensemble of interacting rotors coupled to two leads at different chemical potential letting a current flow through the system and driving it out of equilibrium. We show that at low temperature the coarsening phase persists under the voltage drop up to a critical value of the applied potential that depends on the characteristics of the electron reservoirs. We discuss the properties of the critical surface in the temperature, voltage, strength of quantum fluctuations and coupling to the bath phase diagram. We analyze the coarsening regime finding, in particular, which features are essentially quantum mechanical and which are basically classical in nature. We demonstrate that the system evolves via the growth of a coherence length with the same time-dependence as in the classical limit, $R(t) \simeq t^{1/2}$ -- the scalar curvature driven universality class. We obtain the scaling function of the correlation function at late epochs in the coarsening regime and we prove that it coincides with the classical one once a prefactor that encodes the dependence on all the parameters is factorized. We derive a generic formula for the current flowing through the system and we show that, for this model, it rapidly approaches a constant that we compute.Comment: 53 pages, 12 figure

Crossover from stationary to aging regime in glassy dynamics

We study the non-equilibrium dynamics of the spherical p-spin models in the scaling regime near the plateau and derive the corresponding scaling functions for the correlators. Our main result is that the matching between different time regimes fixes the aging function in the aging regime to $h(t)=\exp(t^{1-\mu})$. The exponent $\mu$ is related to the one giving the length of the plateau. Interestingly $1-\mu$ is quickly very small when one goes away from the dynamic transition temperature in the glassy phase. This gives new light on the interpretation of experiments and simulations where simple aging was found to be a reasonable but not perfect approximation, which could be attributed to the existence of a small but non-zero stretching exponent.Comment: 7 pages+2 figure

Fluctuations in the coarsening dynamics of the O(N) model: are they similar to those in glassy systems?

We study spatio-temporal fluctuations in the non-equilibrium dynamics of the d dimensional O(N) in the large N limit. We analyse the invariance of the dynamic equations for the global correlation and response in the slow ageing regime under transformations of time. We find that these equations are invariant under scale transformations. We extend this study to the action in the dynamic generating functional finding similar results. This model therefore falls into a different category from glassy problems in which full time-reparametrisation invariance, a larger symmetry that emcompasses time scale invariance, is expected to be realised asymptotically. Consequently, the spatio-temporal fluctuations of the large N O(N) model should follow a different pattern from that of glassy systems. We compute the fluctuations of local, as well as spatially separated, two-field composite operators and responses, and we confront our results with the ones found numerically for the 3d Edwards-Anderson model and kinetically constrained lattice gases. We analyse the dependence of the fluctuations of the composite operators on the growing domain length and we compare to what has been found in super-cooled liquids and glasses. Finally, we show that the development of time-reparametrisation invariance in glassy systems is intimately related to a well-defined and finite effective temperature, specified from the modification of the fluctuation-dissipation theorem out of equilibrium. We then conjecture that the global asymptotic time-reparametrisation invariance is broken down to time scale invariance in all coarsening systems.Comment: 57 pages, 5 figure

A Crash Course on Aging

In these lecture notes I describe some of the main theoretical ideas emerged to explain the aging dynamics. This is meant to be a very short introduction to aging dynamics and no previous knowledge is assumed. I will go through simple examples that allow one to grasp the main results and predictions.Comment: Lecture Notes (22 pages) given at "Unifying Concepts in Glass Physics III", Bangalore (2004); to be published in JSTA

Anxiety and Expressed Emotion in a Sample of Obese Patients

INTRODUCTION Expressed Emotion (EE) is a measure of the intensity of the affective family climate and plays a role in disease course and outcome. Especially in urban settings, obesity is a severe problem with serious implications as far as health risks are concerned. Having a high EE caregiver has been suggested to correlate with a worse treatment compliance in obese patients. OBJECTIVES To measure level of EE, stressful events and anxiety in obese patients and their caregivers; to investigate the possible correlations between compliance with treatment and emotional temperature of families. METHODS We have already recruited more than 150 obese patients and their caregivers. Assessment included: Level of Expressed Emotion Scale (LEE), one version for patients and one for relatives in order to evaluate 4 dimensions: intrusiveness, emotional response, attitude toward disease, tolerance and expectation; the Paykel\u2019s Interview for Recent Life Events; STAI Y1 concerning state anxiety and STAI Y2 concerning trait anxiety. Furthermore we collected demographic characteristics and BMI (Body Mass Index). RESULTS Data collection and analyses are still ongoing. Preliminary results suggest a correlation between obesity and level of anxiety. We expect to find a correlation between level of EE and variation of BMI. CONCLUSIONS Levels of EE and anxiety should be considered when planning treatment interventions to enhance compliance in obese patients and to support change in their life-style

The Importance of Cooperation and Relative's Involvement in Combined Treatment for Eating Disorders: a Case Report

Introduction: The importance of combined treatment of EDs is widely acknowledged. We describe the good outcome of a combined treatment in a 43 year old woman, affected by severe Anorexia Nervosa \u2013 Binge Purging (BMI 9.1), since early adolescence. She sought treatment only after giving birth to her second-born when she became aware of her illness. Despite intensive treatment (as an inpatient in hospitals and specialized rehabilitation centres, and in Day Hospital facilities), her condition gradually worsened, and her personal, social, working and family functioning was severely compromised (Global Assessment of Functioning Scale 35), Methods: A multidisciplinary team including psychiatrist, psychotherapist, family psychotherapist, nutritionist, dietician, nurses was involved in treatment, working together to a common treatment strategy. The Psychiatrists role (psicopharmacology, therapeutic process, helping acknowledging and avoiding manipulation) and the nurses role (establishing a therapeutic relationship with the patient, assisting her during meals and supporting the overall therapeutic process), are discussed. Results: A gradual psychopathologic and somatic improvement occurred across a 12-months period: she spent two months in a Psychiatry ward, four more months in a rehab centre and six months in an ED therapeutic community. She gained weight (BMI 21.4) and regained an excellent personal, social and family functioning. She returned to her husband (they previously separated), and the relationship with her daughters, who previously rejected her, improved (GAF 90). Conclusions: The cooperation of the multidisciplinary equipe and the involvement of the patient\u2019s relatives succeeded in reducing anxiety, depression, dysmorphophobia and interrupting the manipulating attitudes typical of the illness

Activated processes and Inherent Structure dynamics of finite-size mean-field models for glasses

We investigate the inherent structure (IS) dynamics of mean-field {\it finite-size} spin-glass models whose high-temperature dynamics is described in the thermodynamic limit by the schematic Mode Coupling Theory for super-cooled liquids. Near the threshold energy the dynamics is ruled by activated processes which induce a logarithmic slow relaxation. We show the presence of aging in both the IS correlation and integrated response functions and check the validity of the one-step replica symmetry breaking scenario in the presence of activated processes. Our work shows: 1) The violation of the fluctuation-dissipation theorem is given by the configurational entropy, 2) The intermediate time regime ($\log(t)\sim N$) in mean-field theory automatically includes activated processes opening the way to analytically investigate activated processes by computing corrections beyond mean-field.Comment: 8 pages, 3 postscript figures, EPL format, improved versio

Driven quantum coarsening

We study the driven dynamics of quantum coarsening. We analyze models of M-component rotors coupled to two electronic reservoirs at different chemical potentials that generate a current threading through the system. In the large M limit we derive the dynamical phase diagram as a function of temperature, strength of quantum fluctuations, voltage and coupling to the leads. We show that the slow relaxation in the ordering phase is universal. On large time and length scales the dynamics are analogous to stochastic classical ones, even for the quantum system driven out of equilibrium at zero temperature. We argue that our results apply to generic driven quantum coarsening.Comment: 4 pages, 3 figure