A bifurcation study to guide the design of a landing gear with a combined uplock/downlock mechanism

This paper discusses the insights that a bifurcation analysis can provide when designing mechanisms. A model, in the form of a set of coupled steady-state equations, can be derived to describe the mechanism. Solutions to this model can be traced through the mechanism's state versus parameter space via numerical continuation, under the simultaneous variation of one or more parameters. With this approach, crucial features in the response surface, such as bifurcation points, can be identified. By numerically continuing these points in the appropriate parameter space, the resulting bifurcation diagram can be used to guide parameter selection and optimization. In this paper, we demonstrate the potential of this technique by considering an aircraft nose landing gear, with a novel locking strategy that uses a combined uplock/downlock mechanism. The landing gear is locked when in the retracted or deployed states. Transitions between these locked states and the unlocked state (where the landing gear is a mechanism) are shown to depend upon the positions of two fold point bifurcations. By performing a two-parameter continuation, the critical points are traced to identify operational boundaries. Following the variation of the fold points through parameter space, a minimum spring stiffness is identified that enables the landing gear to be locked in the retracted state. The bifurcation analysis also shows that the unlocking of a retracted landing gear should use an unlock force measure, rather than a position indicator, to de-couple the effects of the retraction and locking actuators. Overall, the study demonstrates that bifurcation analysis can enhance the understanding of the influence of design choices over a wide operating range where nonlinearity is significant

On the Mean-Field Limit of Bosons with Coulomb Two-Body Interaction

In the mean-field limit the dynamics of a quantum Bose gas is described by a Hartree equation. We present a simple method for proving the convergence of the microscopic quantum dynamics to the Hartree dynamics when the number of particles becomes large and the strength of the two-body potential tends to 0 like the inverse of the particle number. Our method is applicable for a class of singular interaction potentials including the Coulomb potential. We prove and state our main result for the Heisenberg- picture dynamics of "observables”, thus avoiding the use of coherent states. Our formulation shows that the mean-field limit is a "semi-classical” limi

Artefacts and biases affecting the evaluation of scoring functions on decoy sets for protein structure prediction

Motivation: Decoy datasets, consisting of a solved protein structure and numerous alternative native-like structures, are in common use for the evaluation of scoring functions in protein structure prediction. Several pitfalls with the use of these datasets have been identified in the literature, as well as useful guidelines for generating more effective decoy datasets. We contribute to this ongoing discussion an empirical assessment of several decoy datasets commonly used in experimental studies

Controversies Revisited : A Systematic Review of the Comorbidity of Depression and Anxiety with Inflammatory Bowel Diseases.

BACKGROUND: Although mental health concerns are known to occur commonly for those with inflammatory bowel diseases (IBD), the nature of this comorbid relationship has not been systematically reviewed to date. A review in 2007 identified 5 controversies regarding anxiety/depression rates and various comparators between and within IBD. We aimed to systematically analyze and critique the current evidence regarding this comorbidity, providing an update to the 5 controversies. METHODS: Ebscohost Medline, CINAHL, Embase, and PsychINFO were searched between 2005 and 2014 using systematic review methodology. Controlled quantitative studies examining either symptoms or diagnoses of anxiety and depression in IBD were included in the review, with study quality assessed using a scale developed a priori to evaluate observational research. RESULTS: (1) IBD versus healthy controls (pooled mean proportions) (n = 13 studies): anxiety 19.1% versus 9.6%, depression 21.2% versus 13.4%; (2) IBD inactive versus IBD active disease (n = 26): anxiety 28.2% versus 66.4%, depression 19.9% versus 34.7%; (3) ulcerative colitis versus Crohn's disease (n = 28): anxiety 31% versus 37%, depression 22% versus 24.4%; (4) IBD versus other chronic medical conditions (n = 17): anxiety 41.9% versus 48.2%, depression 14.5% versus 28.4%; (5) onset of anxiety/depression before or after IBD onset (n = 2): adults more likely to develop anxiety/depression before IBD onset, but a substantial proportion develops depression after onset; an increased risk for children of developing anxiety/depression after IBD onset. CONCLUSIONS: The high rates of anxiety and depression for those with IBD, particularly when disease is active, warrant a systemic approach to screening and treatmen

Validation of a Digital Support App to Assess Inflammatory Disease Activity and Mental Health Patient-Reported Outcomes (PROs): A Pilot Investigation

Background. Real-time collection of mental health and disease activity patient-reported outcomes (PROs) are essential to assist clinicians in delivering optimal holistic health care. The aim of this pilot study was to validate a digital support tool (DST) delivered via a tablet device in an outpatient setting to assess IBD activity and psychological distress. Methods. 48 individuals (26 females; average age: 40.04) with IBD completed the DST and a paper-based survey in a hospital IBD outpatient setting. PROs for disease activity and psychological distress (Kessler K10) were compared to paper-based gold-standard measures of disease activity (Partial Mayo Index or Harvey Bradshaw Index completed by the clinician) and psychological distress (Depression Anxiety Stress Scale; completed by the patient). Patient feedback regarding usability and acceptance of the DST was also collected. Results. DST patient-derived disease activity scores were significantly correlated with clinician assessment of disease activity (p\u3c0.01). Patient DST-derived psychological well-being scores were also significantly correlated with the gold-standard measure of psychological distress (p\u3c0.05). Patients found the DST to be easy to use and identified a willingness to follow through with the recommendations provided by the DST in relation to their psychological distress scores. Conclusions. The pilot study demonstrates the value in collecting disease activity and psychological distress PROs via a DST in an outpatient setting. Disease activity and psychological distress PROs were found to correlate significantly with gold standard measures. The findings provide preliminary support for the value of embedding digital technology into clinical care to promote patient engagement and optimal holistic healthcare

Faecal microbiota of individuals with autism spectrum disorder

Many children with autistic spectrum disorders (ASDs) suffer from gastrointestinal problems such as diarrhoea, constipation and abdominal pain. Such symptoms may be due to a disruption of the indigenous gut microbiota promoting the overgrowth of potentially pathogenic micro-organisms. These observations have stimulated investigations into possible abnormalities of intestinal microbiota in autistic patients. The purpose of the present study was to determine if a relationship exists between ASD severity (mild – severe) and GI microbial populations. The faecal microbiota of 22 male and 6 female participants with ASDs (aged 7 ± 6 years) were analyzed by standard microbial culture methods and compared within-group (based on ASD severity) and with a standard laboratory reference range. Comparisons between children with mild ASD and those with moderate to severe ASD, as well as comparisons to a neurotypical control group previously reported, revealed that no significant differences appear to exist in the composition of the gut microbiota. Nevertheless, examination of each individual’s gut microbial composition showed 10 cases of unusual findings witch means 1out of 3 cases have unusual microbiota. Our data do not support consistent GI microbial abnormalities in ASD children, but the findings do suggest that aberrations may be found in a minority subset of ASD children. Further studies are required to determine the possible association between the microbiota and gastrointestinal dysfunctions in a subset of children with both ASD and gastro-intestinal problems

Making the journey with me : a qualitative study of experiences of a bespoke mental health smoking cessation intervention for service users with serious mental illness

BACKGROUND: Smoking is one of the major modifiable risk factors contributing to early mortality for people with serious mental illness. However, only a minority of service users access smoking cessation interventions and there are concerns about the appropriateness of generic stop-smoking services for this group. The SCIMITAR (Smoking Cessation Intervention for Severe Mental Ill-Health Trial) feasibility study explored the effectiveness of a bespoke smoking cessation intervention delivered by mental health workers. This paper reports on the nested qualitative study within the trial. METHODS: Qualitative semi-structured interviews were conducted with 13 service users receiving the intervention and 3 of the MHSCPs (mental health smoking cessation practitioners) delivering the intervention. Topic guides explored the perceived acceptability of the intervention particularly in contrast to generic stop-smoking services, and perceptions of the implementation of the intervention in practice. Transcripts were analysed using the Constant Comparative Method. RESULTS: Generic services were reported to be inappropriate for this group, due to concerns over stigma and a lack of support from health professionals. The bespoke intervention was perceived positively, with both practitioners and service users emphasising the benefits of flexibility and personalisation in delivery. The mental health background of the practitioners was considered valuable not only due to their increased understanding of the service users' illness but also due to the more collaborative relationship style they employed. Challenges involved delays in liaising with general practitioners and patient struggles with organisation and motivation, however the MHSCP was considered to be well placed to address these problems. CONCLUSION: The bespoke smoking cessation intervention was acceptable to service users and the both service users and practitioners reported the value of a protected mental health worker role for delivering smoking cessation to this group. The results have wider implications for understanding how to achieve integrated and personalised care for this high-risk population and further underscore the need for sensitised smoking cessation support for people with serious mental illness. TRIAL REGISTRATION: Current Controlled Trials ISRCTN79497236 . Registered 3(rd) July 2009

Fish can show emotional fever: stress-induced hyperthermia in zebrafish

Whether fishes are sentient beings remains an unresolved and controversial question. Among characteristics thought to reflect a low level of sentience in fishes is an inability to show stress-induced hyperthermia (SIH), a transient rise in body temperature shown in response to a variety of stressors. This is a real fever response, so is often referred to as ‘emotional fever’. It has been suggested that the capacity for emotional fever evolved only in amniotes (mammals, birds and reptiles), in association with the evolution of consciousness in these groups. According to this view, lack of emotional fever in fishes reflects a lack of consciousness. We report here on a study in which six zebrafish groups with access to a temperature gradient were either left as undisturbed controls or subjected to a short period of confinement. The results were striking: compared to controls, stressed zebrafish spent significantly more time at higher temperatures, achieving an estimated rise in body temperature of about 2–4°C. Thus, zebrafish clearly have the capacity to show emotional fever. While the link between emotion and consciousness is still debated, this finding removes a key argument for lack of consciousness in fishes