Cellular buckling in I-section struts

An analytical model that describes the interactive buckling of a thin-walled I-section strut under pure compression based on variational principles is presented. A formulation combining the Rayleigh--Ritz method and continuous displacement functions is used to derive a system of differential and integral equilibrium equations for the structural component. Numerical continuation reveals progressive cellular buckling (or snaking) arising from the nonlinear interaction between the weakly stable global buckling mode and the strongly stable local buckling mode. The resulting behaviour is highly unstable and when the model is extended to include geometric imperfections it compares excellently with some recently published experiments.Comment: 23 pages, 12 figures. Submitted for special issue of Thin-Walled Structure

Cellular buckling in stiffened plates

An analytical model based on variational principles for a thin-walled stiffened plate subjected to axial compression is presented. A system of nonlinear differential and integral equations is derived and solved using numerical continuation. The results show that the system is susceptible to highly unstable local--global mode interaction after an initial instability is triggered. Moreover, snap-backs in the response showing sequential destabilization and restabilization, known as cellular buckling or snaking, arise. The analytical model is compared to static finite element models for joint conditions between the stiffener and the main plate that have significant rotational restraint. However, it is known from previous studies that the behaviour, where the same joint is insignificantly restrained rotationally, is captured better by an analytical approach than by standard finite element methods; the latter being unable to capture cellular buckling behaviour even though the phenomenon is clearly observed in laboratory experiments.Comment: 22 pages, 9 figures, 1 table, accepted for publication. Proceedings of the Royal Society A, 201

The treatment of depression and simple phobia through an interpreter in the North East of England : a case study.

A 35-year-old Middle Eastern woman, experiencing moderate depression compounded by animal phobia was referred to an Improving Access to Psychological Therapies (IAPT) service. Shared understandings were gradually developed using written functional analyses translated in session. Activity scheduling was integrated with graded exposure to increase access to positive reinforcement. Questionnaires and subjective data indicated a reduction in phobic avoidance and functioning increased. Despite the complexity of working as a triad, a positive therapeutic relationship was achieved with increased mutual cultural understanding. Indirect communication led to difficulties maintaining guided discovery and focus. There is limited evidence to support CBT when delivered through an interpreter. IAPT recommendations suggest staff reflect the community; the North East has one of the lowest foreign-born populations in the UK indicating that IAPT services may be ill prepared to work with ethnic minorities. Learning points for the therapist were: maintain simplicity, take time to formulate incorporation of cultural difference, and use transcultural interventions. The interpreter brought advantages; providing means of communication and understanding of cultural differences. Disadvantages were the potential for bias or lost information, increased time and complexity of delivering therapy. This case indicates a deficit in high intensity training and lack of literature to support therapists

Well-being of medical students and their awareness on substance misuse: a cross-sectional survey in Pakistan.

Objective: To investigate psychological well-being and substance abuse among medical students in Pakistan. Methods: A cross-sectional questionnaire-based survey was conducted in six medical colleges across Pakistan. Final-year medical students were interviewed by either a postgraduate trainee in psychiatry or a consultant psychiatrist. Results: A total of 540 medical students were approached, 342 participated and the response rate was 64.5%. Mean age was 23.73 years (SD 2.45 years), 52.5% were male and 90% single. Two out of every five respondents reported that work/study at medical school affected their personal health and well-being. A considerable proportion of students were aware of alcohol and smoking as coping strategies for stress in medical students. The main factors causing stress were heavy workload (47.4%), relationship with colleagues (13.5%) and staff (11.9%). A total of 30% reported a history of depression and 15% among them had used an antidepressant. More than half were aware of depression in colleagues. The majority of respondents said that teaching provided on substance misuse in the areas of alcohol and illegal drugs, management/treatment of addiction, and models of addiction was poor. There was significant association (p = 0.044) between stress and awareness about alcohol as a coping strategy for stress among medical students. A significant negative association was also found between medical colleges in public sector (p = 0.052), female gender (p = 0.003) and well-being. Conclusion: The majority of the medical students reported a negative impact of heavy workload on their psychological well-being. Significant numbers of medical students think that substance misuse is a coping strategy for stress. Teaching on addiction/addictive substances is poor at undergraduate level in Pakistani medical colleges

Pattern of benzodiazepine use in psychiatric outpatients in Pakistan: a cross-sectional survey.

Background: Benzodiazepines (BDZ) are the largest-selling drug group in the world. The potential of dependence with BDZ has been known for almost three decades now. In countries like Pakistan where laws against unlicensed sale of BDZ are not implemented vigorously the risk of misuse of and dependence on these drugs is even higher. Previous studies have shown that BDZ prevalence among Patients/visitors to general outPatient clinics in Pakistan may be as high as 30%. However, no research has been carried out on the prevalence of BDZ use in psychiatric Patients in Pakistan. Methods: We carried out a cross-sectional survey over 3 months in psychiatry outPatient clinics of two tertiary care hospitals in Karachi and Lahore. Besides basic socio-demographic data the participants were asked if they were taking a BDZ at present and if yes, the frequency, route and dosage of the drug, who had initiated the drug and why it had been prescribed. We used chi-square test and t-test to find out which socio-demographic or clinical factors were associated with an increased risk of BDZ use. We used Logistic Regression to find out which variable(s) best predicted the increased likelihood of BDZ use. Results: Out of a total of 419 participants 187 (45%) of the participants had been currently using at least one BDZ. Seventy-three percent of the users had been using the drug for 4 weeks or longer and 87% were taking it every day. In 90% of cases the BDZ had been initiated by a doctor, who was a psychiatrist in 70% of the cases. Female gender, increasing age, living in Lahore, and having seen a psychiatrist before, were associated with an increased likelihood of using BDZ. Conclusion: The study shows how high BDZ use is in psychiatric outPatients in Pakistan. Most of the users were taking it for a duration and with a frequency which puts them at risk of becoming dependent on BDZ. In most of the cases it had been initiated by a doctor. Both Patients and doctors need to be made aware of the risk of dependence associated with the use of BDZ