502 research outputs found
Enabling QM-accurate simulation of dislocation motion in ÎłâNi and αâFe using a hybrid multiscale approach
We present an extension of the âlearn on the flyâ method to the study of the motion of dislocations in metallic systems, developed with the aim of producing information-efficient force models that can be systematically validated against reference QM calculations. Nye tensor analysis is used to dynamically track the quantum region centered at the core of a dislocation, thus enabling quantum mechanics/molecular mechanics simulations. The technique is used to study the motion of screw dislocations in Ni-Al systems, relevant to plastic deformation in Ni-based alloys, at a variety of temperature/strain conditions. These simulations reveal only a moderate spacing ( ⌠5 Ă
) between Shockley partial dislocations, at variance with the predictions of traditional molecular dynamics (MD) simulation using interatomic potentials, which yields a much larger spacing in the high stress regime. The discrepancy can be rationalized in terms of the elastic properties of an hcp crystal, which influence the behavior of the stacking fault region between Shockley partial dislocations. The transferability of this technique to more challenging systems is addressed, focusing on the expected accuracy of such calculations. The bcc α â Fe phase is a prime example, as its magnetic properties at the open surfaces make it particularly challenging for embedding-based QM/MM techniques. Our tests reveal that high accuracy can still be obtained at the core of a dislocation, albeit at a significant computational cost for fully converged results. However, we find this cost can be reduced by using a machine learning approach to progressively reduce the rate of expensive QM calculations required during the dynamical simulations, as the size of the QM database increases
Community beliefs about treatments and outcomes of mental disorders: A mental health literacy survey in a rural area of Maharashtra, India
Objectives: Mental health remains a neglected issue in most developing countries, especially in rural areas where access to effective mental health services is limited. The integration of mental health into primary health care is being promoted as a strategy to address this problem. Consequently, there is an urgent need to enhance mental health awareness among communities, and to provide mental health training for primary healthcare staff. In order to do this effectively, it is important to understand and take account of local views on mental health and illness. As such, a mental health literacy (MHL) assessment was undertaken in a poor, rural area of Maharashtra, India to inform the development of a mental health training programme. Study design: A cross-sectional MHL survey was undertaken in late 2007. Methods: Data were collected from 240 systematically sampled community members and 60 purposively sampled village health workers (VHWs) using an interviewer-administered questionnaire. Participants were presented with two vignettes describing people experiencing symptoms of mental disorders (depression, psychosis), and were asked to name the problems, and to identify the treatments and people that were most likely to be helpful (or otherwise), and the likely outcomes for people with such problems. Results: Most participants recognized that the people in the vignettes were experiencing a mental health problem. 'Depression' was the most common label for the problems experienced in the depression vignette, and 'a mind/brain problem' was the most common label in the case of the psychosis vignette. Socio-economic interventions provided by family, friends and neighbours were considered to be most helpful. Local VHWs and doctors were also viewed as potentially helpful, but psychiatrists less so. Approximately half of the sample thought that dealing with the problem alone would be helpful. Special diets, tonics, appetite stimulants and sleeping pills were also strongly endorsed, but awareness of psychiatric medications was negligible. Conclusion: The findings from this study highlight the need to enhance MHL in this community. Additionally, there is a need to build the capacity of the primary healthcare staff, including the VHWs, so that they are equipped to provide an effective local response for people experiencing mental health problems
Attitudes to people with mental disorders: a mental health literacy survey in a rural area of Maharashtra, India
Introduction: People with mental disorders experience discrimination as a consequence of stigmatising attitudes that are largely socio-culturally constructed. Thus, there is a need to understand local contexts in order to develop effective programs to change such attitudes. We undertook a mental health literacy survey in rural Maharashtra, India, prior to developing a mental health training program for village health workers (VHWs) in a primary health care setting. Methods: A cross-sectional mental health literacy survey was undertaken in late 2007, which involved interviewer-administration of a questionnaire to 240 systematically sampled community members, and 60 purposively sampled VHWs. Participants were presented with two vignettes describing people experiencing symptoms of mental disorders (depression, psychosis), and were asked about attitudes towards, and desired social distance from, the people in the vignettes (the latter being a proxy measure for stigma). Linear regression modelling was undertaken to identify predictors of social distance. Results: Although the community was relatively accepting of people with mental disorders, false beliefs and negative attitudes were still evident. Desired social distance was consistently greater for the person depicted in the psychosis vignette compared to the depression vignette. For both vignettes, the main predictor of greater social distance was perceiving the person as dangerous, and the predictors of reduced social distance were being a VHW, and seeing the problem as a sign of personal weakness. For depression, believing the cause to be family tensions also reduced social distance. For psychosis, labelling the disorder as a mind/brain problem, and believing the cause to be lack of control over life or genetic factors increased social distance. The vast majority did not agree that the problems experienced in the vignettes were 'a real medical illness'. Conclusion: Promoting bio-medical explanations for mental disorders in this setting may exacerbate discriminatory attitudes. Provision of contextually relevant mental health training for the VHWs so that they are able to communicate, model and shape more positive attitudes is the next step
A mental health training program for community health workers in India: impact on knowledge and attitudes
<p>Abstract</p> <p>Background</p> <p>Unmet needs for mental health treatment in low income countries are pervasive. If mental health is to be effectively integrated into primary health care in low income countries like India then grass-roots workers need to acquire relevant knowledge and skills to be able to recognise, refer and support people experiencing mental disorders in their own communities. This study aims to provide a mental health training intervention to community health workers in Bangalore Rural District, Karnataka, India, and to evaluate the impact of this training on mental health literacy.</p> <p>Methods</p> <p>A pre-test post-test study design was undertaken with assessment of mental health literacy at three time points; baseline, completion of the training, and three month follow-up. Mental health literacy was assessed using the interviewer-administered Mental Health Literacy Survey. The training intervention was a four day course based on a facilitator's manual developed specifically for community health workers in India.</p> <p>Results</p> <p>70 community health workers from Doddaballapur, Bangalore Rural District were recuited for the study. The training course improved participants' ability to recognize a mental disorder in a vignette, and reduced participants' faith in unhelpful and potentially harmful pharmacological interventions. There was evidence of a minor reduction in stigmatizing attitudes, and it was unclear if the training resulted in a change in participants' faith in recovery following treatment.</p> <p>Conclusion</p> <p>The findings from this study indicate that the training course demonstrated potential to be an effective way to improve some aspects of mental health literacy, and highlights strategies for strengthening the training course.</p
Aesthetics and literature : a problematic relation?
The paper argues that there is a proper place for literature within aesthetics but that care must be taken in identifying just what the relation is. In characterising aesthetic pleasure associated with literature it is all too easy to fall into reductive accounts, for example, of literature as merely "fine writing". Belleslettrist or formalistic accounts of literature are rejected, as are two other kinds of reduction, to pure meaning properties and to a kind of narrative realism. The idea is developed that literature-both poetry and prose fiction-invites its own distinctive kind of aesthetic appreciation which far from being at odds with critical practice, in fact chimes well with it
Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum
Hydrogen embrittlement is a complex phenomenon, involving several length- and timescales, that affects a large class of metals. It can significantly reduce the ductility and load-bearing capacity and cause cracking and catastrophic brittle failures at stresses below the yield stress of susceptible materials. Despite a large research effort in attempting to understand the mechanisms of failure and in developing potential mitigating solutions, hydrogen embrittlement mechanisms are still not completely understood. There are controversial opinions in the literature regarding the underlying mechanisms and related experimental evidence supporting each of these theories. The aim of this paper is to provide a detailed review up to the current state of the art on the effect of hydrogen on the degradation of metals, with a particular focus on steels. Here, we describe the effect of hydrogen in steels from the atomistic to the continuum scale by reporting theoretical evidence supported by quantum calculation and modern experimental characterisation methods, macroscopic effects that influence the mechanical properties of steels and established damaging mechanisms for the embrittlement of steels. Furthermore, we give an insight into current approaches and new mitigation strategies used to design new steels resistant to hydrogen embrittlement
IgG 3 + B cells are associated with the development of multiple sclerosis
Objectives
Diseaseâmodifying therapies (DMTs) targeting B cells are amongst the most effective for preventing multiple sclerosis (MS) progression. IgG3 antibodies and their uncharacterised Bâcell clones are predicted to play a pathogenic role in MS. Identifying subsets of IgG3+ B cells involved in MS progression could improve diagnosis, could inform timely disease intervention and may lead to new DMTs that target B cells more specifically.
Methods
We designed a 31âparameter Bâcellâfocused mass cytometry panel to interrogate the role of peripheral blood IgG3+ B cells in MS progression of two different patient cohorts: one to investigate the Bâcell subsets involved in conversion from clinically isolated syndrome (CIS) to MS; and another to compare MS patients with inactive or active stages of disease. Each independent cohort included a group of nonâMS controls.
Results
Nine distinct CD20+IgDâIgG3+ Bâcell subsets were identified. Significant changes in the proportion of CD21+CD24+CD27âCD38â and CD27+CD38hiCD71hi memory Bâcell subsets correlated with changes in serum IgG3 levels and time to conversion from CIS to MS. The same CD38â doubleânegative Bâcell subset was significantly elevated in MS patients with active forms of the disease. A third CD21+CD24+CD27+CD38â subset was elevated in patients with active MS, whilst narrowband UVB significantly reduced the proportion of this switchedâmemory Bâcell subset.
Conclusion
We have identified previously uncharacterised subsets of IgG3+ B cells and shown them to correlate with autoimmune attacks on the central nervous system (CNS). These results highlight the potential for therapies that specifically target IgG3+ B cells to impact MS progression
Lymphocyte reconstitution following autologous stem cell transplantation for progressive MS
BACKGROUND:
Autologous stem cell transplantation (ASCT) for progressive multiple sclerosis (MS) may reset the immune repertoire.
OBJECTIVE:
The objective of this paper is to analyse lymphocyte recovery in patients with progressive MS treated with ASCT.
METHODS:
Patients with progressive MS not responding to conventional treatment underwent ASCT following conditioning with high-dose cyclophosphamide and antithymocyte globulin. Lymphocyte subset analysis was performed before ASCT and for two years following ASCT. Neurological function was assessed by the EDSS before ASCT and for three years post-ASCT.
RESULTS:
CD4+ T-cells fell significantly post-transplant and did not return to baseline levels. Recent thymic emigrants and naĂŻve T-cells fell sharply post-transplant but returned to baseline by nine months and twelve months, respectively. T-regulatory cells declined post-transplant and did not return to baseline levels. Th1 and Th2 cells did not change significantly while Th17 cells fell post-transplant but recovered to baseline by six months. Neurological function remained stable in the majority of patients. Progression-free survival was 69% at three years.
CONCLUSION:
This study demonstrates major changes in the composition of lymphocyte subsets following ASCT for progressive MS. In particular, ablation and subsequent recovery of thymic output is consistent with the concept that ASCT can reset the immune repertoire in MS patients
Narrative and Interpretation on Twitter: Reading tweets by telling stories
Existing research on communication on Twitter has largely ignored the question of how users make sense of the fragmentary tweets with which they are presented. Focusing on the use of Twitter for political reporting in post-revolutionary Egypt, this article argues that the production of mental stories provides readers with a mechanism for interpreting the meaning of individual tweets in terms of their relationships to other material. Drawing on contemporary narratology, it argues that Twitter exhibits key elements of narrativity, but that a creative reading process is nonetheless required to transform this incipient narrativity into coherent, sense-making mental narratives. This foregrounding of the readerâs creative role makes stories on Twitter highly fluid and dynamic. Through reference to classic critical theory, I propose that this nonetheless represents an evolution rather than a radical break from earlier forms of narrative reception, which in many cases demanded similarly creative reading practices
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