Elastic and anelastic relaxations in the relaxor ferroelectric Pb(Mg1/3Nb2/3)O3: II. Strain-order parameter coupling and dynamic softening mechanisms.

Elastic and anelastic behaviour of single crystal and ceramic samples of Pb(Mg(1/3)Nb(2/3))O(3) has been investigated at frequencies of ~0.1-1.2 MHz through the temperature interval 10-800 K by resonant ultrasound spectroscopy (RUS). Comparison with data from the literature shows that softening of the shear modulus between the Burns temperature and the freezing interval is independent of frequency. The softening is attributed to coupling between acoustic modes and the relaxation mode(s) responsible for central peaks in Raman and neutron scattering spectra below the Burns temperature, and can be described with Vogel-Fulcher parameters. Shear elastic compliance and dielectric permittivity show similar patterns of temperature dependence through the freezing interval, demonstrating strong coupling between ferroelectric polarization and strain such that the response to applied stress is more or less the same as the response to an applied electric field, with a frequency dependence consistent with Vogel-Fulcher-like freezing in both cases. Differences in detail show, however, that shearing induces flipping between different twin orientations, in comparison with the influence of an electric field, which induces 180° flipping: the activation energy barrier for the former appears to be higher than for the latter. Below the freezing interval, the anelastic loss also has a similar pattern of evolution to the dielectric loss, signifying again that essentially the same mechanism is involved in the freezing process. Overall softening at low temperatures is attributed to the contributions of strain relaxations due to coupling with the local ferroelectric order parameter and of coupling between acoustic modes and continuing relaxational modes of the polar nanostructure. Dissipation is attributed to movement of boundaries between PNRs or between correlated clusters of PNRs. Overall, strain coupling is fundamental to the development of the characteristic strain, dielectric and elastic properties of relaxors.

Engaging Australian physicians in evidence-based medicine: a representative national survey.

AIM: To assess Australian adult physicians' views about evidence-based medicine (EBM) and quality improvement (QI). BACKGROUND: Cross-sectional postal survey of two hundred and forty-four randomly selected Australian physicians (78.5% response rate). METHOD: Physicians' views about the promotion of EBM and QI and their impact on patient care, strategies to support better clinical practice and self-reported understanding of EBM terms. RESULTS: Sixty-eight per cent (95% confidence interval (CI): 62-74%) of physicians had a positive view of the current promotion of EBM in Australia. Significantly fewer (45%; 95% CI: 38-51%) were so positive about QI (P <0.001). Although 74% (95% CI: 68-79%) indicated that EBM improves patient care, significantly fewer (46%; 95% CI: 40-53%) held this view with respect to QI (P <0.001). Although 70% (95% CI: 64-76%) of physicians agreed they had adequate skills to search for evidence, significantly fewer (21%; 95% CI: 17-27%) agreed they had sufficient time to do so (P <0.001). EBM skills were positively associated with involvement in teaching. Physicians were significantly more positive about approaches exclusive to themselves compared with those involving other disciplines. CONCLUSIONS: Although Australian physicians have positive views of EBM, QI appears less well regarded. Initiatives to improve quality and safety that incorporate principles and language of EBM will likely be received better by physicians than isolated QI. Further enhancement of EBM requires concomitant attention to physician training, workplace infrastructure and supportive professional development.

Posttraumatic stress disorder. Safe, effective management in the primary care setting.

PTSD is a severe and chronic psychiatric condition. Because of the complex symptoms, no single treatment is effective. Pharmacologic treatment is an integral component of a multidisciplinary approach that addresses the psychological, social, and spiritual dimensions of PTSD. Psychopharmacologic agents provide symptomatic relief and are beneficial in managing other comorbid psychiatric conditions. Primary care physicians can base treatment decisions on the patient's prevailing symptoms. Specialized psychiatric consultation may be needed in difficult and complicated cases.

The clinical experience of citalopram in the treatment of post-traumatic stress disorder: a report of two Persian Gulf War veterans.

OBJECTIVE: To determine the efficacy of the antidepressant citalopram in the treatment of post-traumatic stress disorder (PTSD). METHOD: The cases of two Persian Gulf War veterans are described to illustrate the effects of citalopram in treating their PTSD symptoms. RESULTS: In these two clinical case studies, citalopram led to remission of some of the PTSD symptoms. CONCLUSION: More controlled studies are warranted to further prove the efficacy of citalopram as an agent of choice for the treatment of PTSD.

Appendicectomy in Western Australia: profile and trends, 1981-1997.

OBJECTIVE: To measure and describe changes in the incidence of appendicectomy in the population of Western Australia (WA) for 1981-1997. DESIGN: Population-based incidence study using hospital discharge data. SETTING: All hospitals in WA (1981-1997). PATIENTS: All patients who underwent an appendicectomy in WA hospitals. MAIN OUTCOME MEASURES: Changes in the incidence of appendicectomy procedures over time; age-standardised rates and age-sex profiles of four appendicectomy subgroups: (1) acute emergency admission, (2) other emergency admission, (3) incidental appendicectomy and (4) other appendicectomy. RESULTS: From 1981 to 1997, there were 59,749 appendicectomies in WA hospitals. The age-standardised rate of appendicectomy declined by 63% in metropolitan females, by 44% in non-metropolitan females, by 41% in metropolitan males and by 21% in non-metropolitan males. The rate of decline was significantly greater in females and in metropolitan patients. From 1988 to 1997, acute emergency admission for appendicectomy was the most common admission status and was more common in males than females (122 v 103 per 100,000 person-years) and in non-metropolitan areas. The rate of incidental appendicectomy was higher among females than males (20 v 7 per 100,000 person-years). From 1988 to 1997, recorded diagnosis coding for appendicitis became more specific, with a marked reduction in the use of the "unspecified" appendicitis code. CONCLUSIONS: The overall incidence of appendicectomy has declined markedly in WA and includes a decline in the practice of incidental appendicectomy. The trend was greatest in the metropolitan hospitals.

Initial results of ultrasound screening for aneurysm of the abdominal aorta in Western Australia: relevance for endoluminal treatment of aneurysm disease.

BACKGROUND: Increased life expectancy in men during the last thirty years is largely due to the decrease in mortality from cardiovascular disease in the age group 29--69 yr. This change has resulted in a change in the disease profile of the population with conditions such as aneurysm of the abdominal aorta (AAA) becoming more prevalent. The advent of endoluminal treatment for AAA has encouraged prophylactic intervention and fueled the argument to screen for the disease. The feasibility of inserting an endoluminal graft is dependent on the morphology and growth characteristics of the aneurysm. This study used data from a randomized controlled trial of ultrasound screening for AAA in men aged 65--83 yr in Western Australia for the purpose of determining the norms of the living anatomy in the pressurized infrarenal aorta. AIMS: To examine (1) the diameters of the infra-renal aorta in aneurysmal and non-aneurysmal cases, (2) the implications for treatment modalities, with particular reference to endoluminal grafting, which is most dependent on normal and aneurysmal morphology, and (3) any evidence to support the notion that northern Europeans are predisposed to aneurysmal disease. METHODS: Using ultrasound, a randomized control trial was established in Western Australia to assess the value of a screening program in males aged 65--83 yr. The infra-renal aorta was defined as aneurysmal if the maximum diameter was 30 mm or more. Aortic diameter was modelled both as a continuous (in mm) and as a binary outcome variable, for those men who had an infra-renal diameter of 30 mm or more. ANOVA and linear regression were used for modelling aortic diameter as a continuum, while chi-square analysis and logistic regression were used in comparing men with and without the diagnosis of AAA. FINDINGS: By December 1998, of 19,583 men had been invited to undergo ultrasound screening for AAA, 12,203 accepted the invitation (corrected response fraction 70.8%). The prevalence of AAA increased with age from 4.8% at 65 yr to 10.8% at 80 yr (chi(2)=77.9, df=3, P<0.001). The median (IQR) diameter for the non-aneurysmal group was 21.4 mm (3.3 mm) and there was an increase (chi(2)=76.0, df=1, P<0.001) in the diameter of the infra-renal aorta with age. Since 27 mm is the 95th centile for the non-aneurysmal infra-renal aorta, a diameter of 30 mm or more is justified as defining an aneurysm. The risk of AAA was higher in men of Australian (OR=1.0) and northern European origin (OR=1.0, 95%CL: 0.9, 1.2) compared with those of Mediterranean origin (OR=0.5, 95%CL: 0.4, 0.7). CONCLUSION: Although screening has not yet been shown to reduce mortality from AAA, these population-based data assist the understanding of aneurysmal disease and the further development and use of endoluminal grafts for this condition.

Validation of women's self-reported smoking status in a Sydney colposcopy clinic.

This study validated a self-reported smoking prevalence questionnaire against urinary cotinine levels among women referred to a Sydney based public hospital colposcopy clinic over the period November 1997 to June 1998. Of 213 eligible women, 160 (75%) agreed to participate. Of these, 151 (94%) completed the smoking prevalence item and 130 (86%) also provided a urine specimen. 40% (95% CI: 33%-49%) of respondents self-reported as current smokers. Observed agreement between self-reported and biochemically validated smoking status was 94% compared with 52% chance agreement (kappa = 0.87, p<0.001). This high level of agreement was also robust to sensitivity analyses using a more conservative cutoff for the urinary cotinine levels. We conclude that self-reported smoking status provides valid estimates of actual rates of smoking among women referred with abnormal cervical smears.

Psychiatric morbidity in HIV patients.

OBJECTIVE: To provide an accessible source of clinical information related to the diagnosis and treatment of psychiatric morbidity associated with HIV infection. METHOD: A selective MEDLINE literature search was used to identify 225 relevant articles, 67 of which were selected for inclusion based upon the presence of psychiatric morbidity. Psychiatric morbidity was defined by the presence of a DSM-IV diagnostic code reflecting psychiatric illness. RESULTS: HIV-infected patients have high rates of psychiatric morbidity. CONCLUSION: The psychiatric evaluation and treatment of psychiatric morbidity improve the quality of life of HIV and AIDS patients.