On the constitutive modeling of dual-phase steels at finite strains: a generalized plasticity based approach

In this work we propose a general theoretic framework for the derivation of constitutive equations for dual-phase steels, undergoing continuum finite deformation. The proposed framework is based on the generalized plasticity theory and comprises the following three basic characteristics: 1.A multiplicative decomposition of the deformation gradient into elastic and plastic parts. 2.A hyperelastic constitutive equation 3.A general formulation of the theory which prescribes only the number and the nature of the internal variables, while it leaves their evolution laws unspecified. Due to this generality several different loading functions, flow rules and hardening laws can be analyzed within the proposed framework by leaving its basic structure essentially unaltered. As an application, a rather simple material model, which comprises a von-Mises loading function, an associative flow rule and a non-linear kinematic hardening law, is proposed. The ability of the model in simulating simplified representation of the experimentally observed behaviour is tested by two representative numerical examples

On the constitutive modeling of dual-phase steels at finite strains: a generalized plasticity based approach

In this work we propose a general theoretic framework for the derivation of constitutive equations for dual-phase steels, undergoing continuum finite deformation. The proposed framework is based on the generalized plasticity theory and comprises the following three basic characteristics: 1.A multiplicative decomposition of the deformation gradient into elastic and plastic parts. 2.A hyperelastic constitutive equation 3.A general formulation of the theory which prescribes only the number and the nature of the internal variables, while it leaves their evolution laws unspecified. Due to this generality several different loading functions, flow rules and hardening laws can be analyzed within the proposed framework by leaving its basic structure essentially unaltered. As an application, a rather simple material model, which comprises a von-Mises loading function, an associative flow rule and a non-linear kinematic hardening law, is proposed. The ability of the model in simulating simplified representation of the experimentally observed behaviour is tested by two representative numerical examples

Excessive weight gain after remission of depression in a schizophrenic patient treated with risperidone: case report

BACKGROUND: The use of atypical antipsychotics in schizophrenic patients has been associated with a risk of weight gain. Similarly, recovery from depression is often followed by improved appetite, greater food intake and potential increase in weight. CASE PRESENTATION: A Caucasian 33-year-old schizophrenic female patient was being treated with 6 mg/day of risperidone and 15 mg/day of clorazepate. She developed depressive symptomatology and 40 mg/day of fluoxetine was gradually added to her treatment regimen for about 9 months. After the remission of depression, and the discontinuation of fluoxetine, she experienced an increase in appetite and subsequently excessive weight gain of 52 kg. Re-administration of fluoxetine did not reverse the situation. The patient developed diabetes mellitus, which was successfully controlled with metformin 1700 mg/day. The addition at first of orlistat 360 mg/day and later of topiramate 200 mg/day has helped her to lose a significant part of the weight gained (30 kg). CONCLUSION: The case suggests a probable association between the remission of depressive symptomatology and weight gain in a schizophrenic patient

On Spatial Covariance, Second Law of Thermodynamics and Configurational Forces in Continua

This paper studies the transformation properties of the spatial balance of energy equation for a dissipative material, under the superposition of arbitrary spatial diffeomorphisms. The study reveals that for a dissipative material the transformed energy balance equation has some non-standard terms in it. These terms are related to a system of microforces with its own balance equation. These microforces act during the superposition of the spatial diffeomorphism, because of the dissipative properties of the material. Moreover, it is shown that for the case in question the stress tensor is additively decomposed into a conventional part given by the standard Doyle-Ericksen formula and a non-conventional one which is related to changes in the material internal structure in the course of deformation. On the basis of the second law of thermodynamics and the integrability condition of a Pfaffian form it is shown that the non-conventional part of the stress tensor can be related not only to dissipative but also to conservative response. A further insight to this conservative response is provided by exploiting the invariance properties of the balance of energy equation within the context of the material intrinsic “physical” metric concept. In this case, it is shown that the assumption of spatial covariance yields the standard conservation and balance laws of classical mechanics but it does not yield the standard Doyle-Ericksen formula. In fact, the Doyle-Ericksen formula has an additional term in it, which is related directly to the evolution of the material internal structure, as it is determined by the (time) evolution of the material metric in the spatial configuration. A formal connection between this term and the Eshelby energy-momentum tensor is derived as well

On the quasi-yield surface concept in plasticity theory

In this paper we provide deeper insights into the concept of the quasi-yield surface in plasticity theory. More specifically, in this work, unlike the traditional treatments of plasticity where special emphasis is placed on an unambiguous definition of a yield criterion and the corresponding loading-unloading conditions, we place emphasis on the study of a general rate equation which is able to enforce elastic-plastic behavior. By means of this equation we discuss the fundamental concepts of the elastic range and the elastic domain. The particular case in which the elastic domain degenerates into its boundary leads to the quasi-yield surface concept. We exploit this concept further by discussing several theoretical issues related to it and by introducing a simple material model. The ability of the model in predicting several patterns of the real behavior of metals is assessed by representative numerical examples

Non-pharmacological treatments in the management of rapid cycling bipolar disorder

Background: Rapid cycling (RC) bipolar disorder is often treatment-resistant to pharmacotherapy. Non-pharmacological methods, however, are reasonable considerations in treatment refractory cases of bipolar patients. Thus, such methods may be useful in the management of RC, especially when drugs are not shown to be effective. Method: This review is based on studies of all major non-pharmacological methods which are used in the management of bipolar disorder, by focusing on data regarding patients with a RC pattern of the illness. Results: Regarding biological treatments, for electroconvulsive therapy and sleep deprivation, there exists some evidence that they might be efficacious in RC patients for acute treatment as well as for prophylaxis from recurrences. Light therapy has not been shown to be efficacious in RC, while no published data exist for transcranial magnetic stimulation and vagus nerve stimulation. The non-biological treatments include psychotherapeutic and psychosocial interventions; these have not been tried particularly on RC patients, but their use should be expected to contribute to the overall management of the RC pattern as it does to that of mood disorder in general. Limitations: Many data on which this review is based are drawn from case reports or non-randomised trials. Conclusions: Non-pharmacological methods, either biological or non-biological (psychotherapies and psychoeducation), may be applied in the management of RC patients. These methods might be used in combination with the administration of drug treatment, based on the clinical experience of the physician and the individual characteristics of the patient. (c) 2006 Elsevier B.V. All rights reserved

The psychological impact of a catastrophic earthquake - A retrospective study 50 years after the event

Aim of the present study was to retrospectively assess the impact of a catastrophic earthquake in a sample of 121 survivors, 50 years after the event. Mean age +/- SD of the responders was 72.2 +/- 6.1 years. The majority of the victims (78%) acknowledged a strong overall impact of the earthquake on their lives, and almost all of them had intense recollection of the event at its anniversary. The most frequent symptom during the 6 months after the earthquake was persistent remembering or “reliving” of the event; women had considerably more often recurrent dreams of the earthquake and distress than did men. Women and young adults at the time of the earthquake appear to be the most vulnerable groups regarding the psychological effects of the event

Excessive weight gain after remission of depression in a schizophrenic patient treated with risperidone: case report

Abstract Background The use of atypical antipsychotics in schizophrenic patients has been associated with a risk of weight gain. Similarly, recovery from depression is often followed by improved appetite, greater food intake and potential increase in weight. Case presentation A Caucasian 33-year-old schizophrenic female patient was being treated with 6 mg/day of risperidone and 15 mg/day of clorazepate. She developed depressive symptomatology and 40 mg/day of fluoxetine was gradually added to her treatment regimen for about 9 months. After the remission of depression, and the discontinuation of fluoxetine, she experienced an increase in appetite and subsequently excessive weight gain of 52 kg. Re-administration of fluoxetine did not reverse the situation. The patient developed diabetes mellitus, which was successfully controlled with metformin 1700 mg/day. The addition at first of orlistat 360 mg/day and later of topiramate 200 mg/day has helped her to lose a significant part of the weight gained (30 kg). Conclusion The case suggests a probable association between the remission of depressive symptomatology and weight gain in a schizophrenic patient.</p